In the past, I have taken part in some of the traditions of Khmer New Year celebrations. Being a "seasoned" ex-pat, I'm less inclined to join in on the festivities, leaving it up to the "newbies" in town. I have played my fair share of "Bos Angkunh" and danced around tables, though I doubt anyone actually captured it on film.
Here are some great explanations from Wikipedia (the photos are mine):
Cambodian New Year (Khmer: បុណ្យចូលឆ្នាំថ្មី) or Chaul Chnam Thmey in the Khmer language, literally "Enter Year New", is the name of the Cambodian holiday that celebrates the New Year. The holiday lasts for three days beginning on New Year's day, which usually falls on April 13th or 14th, which is the end of the harvesting season, when farmers enjoy the fruits of their labor before the rainy season begins. Khmer's living abroad may choose to celebrate during a weekend rather than just specifically April 13th through 15th. The Khmer New Year coincides with the traditional solar new year in several parts of India, Myanmar and Thailand.Cambodians also use Buddhist Era to count the year based on the Buddhist calendar. For 2011, it is 2555 BE (Buddhist Era).
In temples, people erect a sand hillock on temple grounds. They mound up a big pointed hill of sand or dome in the center which represents sakyamuni satya, the stupa at Tavatimsa, where the Buddha's hair and diadem are buried. The big stupa is surrounded by four small ones, which represent the stupas of the Buddha's favorite disciples: Sariputta, Moggallana, Ananda, and Maha Kassapa. There is another tradition called Sraung Preah (ស្រង់ព្រះ) : pouring water or liquid plaster (a mixture of water with some chalk powder) on elder relative, or people (mostly the younger generation is responsible for pouring the water).
The Khmer New Year is also a time to prepare special dishes. One of these is a "kralan": a cake made from steamed rice mixed with beans or peas, grated coconut and coconut milk. The mixture is stuffed inside a bamboo stick and slowly roasted.
Khmer games (ល្បែងប្រជាប្រិយ)
Cambodia is home to a variety of games played to transform the dull days into memorable occasions. These games are similar to those played at Manipur, a north-eastern state in India.  Throughout the Khmer New Year, street corners often are crowded with friends and families enjoying a break from routine, filling their free time with dancing and games. Typically, Khmer games help maintain one's mental and physical dexterity. The body's blood pressure, muscle system and brain are challenged and strengthened for fun.
A game played by throwing and catching a ball with one hand while trying to catch an increasing number of sticks with the other hand. Usually, pens or chopsticks are used as the sticks to be caught.
- "Chol Chhoung (ចោលឈូង) "
A game played especially on the first nightfall of the Khmer New Year by two groups of boys and girls. Ten or 20 people comprise each group, standing in two rows opposite each other. One group throws the "chhoung" to the other group. When it is caught, it will be rapidly thrown back to the first group. If someone is hit by the "chhoung," the whole group must dance to get the "chhoung" back while the other group sings.
- "Chab Kon Kleng (ចាប់កូនខ្លែង) "
A game played by imitating a hen as she protects her chicks from a crow. Adults typically play this game on the night of the first New Year's Day. Participants usually appoint a strong player to play the hen who protects "her" chicks, while another person is picked to be the "crow". While both sides sing a song of bargaining, the crow tries to catch as many chicks as possible as they hide behind the hen.
- "Bos Angkunh (បោះអង្គុញ)"
A game played by two groups of boys and girls. Each group throws their own "angkunh" to hit the master "angkunhs," which belong to the other group and are placed on the ground. The winners must knock the knees of the losers with the "angkunh." "Angkunh" is also the name of an inedible fruit seed, which looks like a knee bone.
- "Leak Kanseng (លាក់កន្សែង) "
A game played by a group of children sitting in a circle. Someone holding a "kanseng" (Cambodian towel) that is twisted into a round shape walks around the circle while singing a song. The person walking secretly tries to place the "kanseng" behind one of the children. If that chosen child realizes what is happening, he or she must pick up the "kanseng" and beat the person sitting next to him or her.
- "Bay Khom(បាយខុម)"
A game played by two children in rural or urban areas during their leisure time. Ten holes are dug in the shape of an oval into a board in the ground. The game is played with 42 small beads, stones or fruit seeds. Before starting the game, five beads are put into each of the two holes located at the tip of the board. Four beads are placed in each of the remaining eight holes. The first player takes all the beads from any hole and drops them one by one in the other holes. He or she must repeat this process until they have dropped the last bead into a hole that lies besides any empty one. Then they must take all the beads in the hole that follows the empty one. At this point, the second player may have his turn. The game ends when all the holes are empty. The player with the greatest number of beads wins the game. It is possibly similar to congkak.
- "Klah Klok (ខ្លា ឃ្លោក) "
A game played by Cambodians of all ages. It is a gambling game that is fun for all ages involving a mat and some dice. You put money on the object that you believe the person rolling the dice (which is usually shaken in a type of bowl) and you wait. If the objects face up on the dice are the same as the objects you put money on, you double it. If there are two of yours, you triple, and so on.