I recommend the film "Đừng đốt" (Don't burn) which won the audience prize at the International 19th Annual Film Festival in Fukuoka, Japan. It's a moving story about the young doctor Đặng Thùy Trâm.
http://www.youtube.com/watch?v=iGoMQI80BH8
Click on CC
Then find the "Vietnamese"
BAM there you have it! Vietnamese subtitles!
"The Rebel" is very good. ^^ It's called " Dòng máu anh hùng" in Vietnamese. ^^
To start with, I will recommend you watch a short-film (having Eng sub), which is socalled the most popular film watched by the young recently!
I think a short-film is easier for you to understand! However, the problem is that the actors in that film have the accent of the Southern Viet Nam! It may be quite hard to listen!
Please give me your Gmail and I can share my Google drive, I have made a store of Vietnamese films with English subtitles there.