Hi all, this is my first post =)

I am on a multimedia tutorial flash project, something like teach you how to use EXCEL with some screenshot and video(a guy talk something).

my approach is as following,

Backbone swf:
1) import a XML which is all about the list of movies needed in a chapter.

2) duplicate movies from a container and load scene into each of them.(there are 3 movies in a chapter for example)

3) when the movies are loading, i set the alpha of the containers of each individual to zero, and stop it of course.

4) when loading of first movie is done, I start play the movie and go on.(play() & _alpha=100).

seems the approach works fine, as the file size of each MC is not really big... like 500k-1.5m for video.

but I experienced problem when press "previous movie" button.
Scenerio is this:
first MC is a video, second & third are screenshot movies.

When i press previous, I set the 2, 3 movies as _alpha=0 & gotoAndStop(1), then play the first movie as usual.

however, the sound and picture not sync when i play again the first movie by "previous button".

So what is the problem on this?
Please kindly give your helping hands.

PS: I am not native english speaker so pls let me know if i am not expressed clear enough. tks. =)