I figure I'd criticize your use of weaponry. I've got nothing better to do, so I'll pick it apart.
1. Your fingers were on the triggers even when you weren't firing. First rule of weapons, fingers off the trigger until ready to fire.
2. Around 6:45 the character at the end of the line is carrying an M249 variant, which weren't introduced until the early 80s.
3. At 7:49 you see an AK-74, not an AK-47. The AK-74 was never used in Vietnam as it wasn't introduced until, you guessed it, 1974.
4. Throughout the film you can see a character carrying an M4A1. It COULD be an XM177 / CAR-15, but due to the placement of the forward assist, not to mention the fact that it simply looks like an airsoft replica, I'd say that could fall under the ranks of historical inaccuracies.
5. The ghillie suite used is a modern standard. In Vietnam snipers would very rarely used ghillie suites due to infection risks as well as heat exhaustion. Soldiers would commonly lay under large leaves, especially during the rainy season, when sniping.
Now for actual film criticism itself:
1. The audio was WAY too loud. I have my headphones set to 10, which is the lowest you can go on them without turning them off, and it was still relatively loud.
2. Adjust your white-balance. It looked like you were shooting a webcam film.
3. Use more camera angles, quicker shots, and don't focus on a single subject for more than 30 seconds. If you were shooting a comedy or informative video, it'd be fine to use longer, but action videos are best shot with short shots, and a lot of area for people to go, "What is going on?"
4. Blend the effects better. Too many times people make / acquire CGI effects, and don't apply them properly. They are meant to blend in with the environment / lighting schema. You should NOT have bright muzzle flashes like that, they look rather unrealistic.
Other than those things, it's not a bad no-budget film.
I just now realized I've had a typo in my signature for the past 3 years.
