avi is not a codec, it's a container. What tool did you use to encode and export as avi ? What preset / specs did you use ?
From what I understand after effects supports .avi files but it seems to be really picky about them.
The trial versions of Adobe After Effects® CS5, Adobe Premiere® Pro CS5, and Soundbooth® CS5 software do not include some features that depend on software licensed from parties other than Adobe. For example, some codecs for encoding MPEG formats are available only with the full version of these products.
Applies to all older versions thatr run in trial mode just as well. That aside, Seb is right - just mentioning AVIs is a futile exercise. Without info on what CoDecs were used this is going nowhere. If it's a specific third-party CoDec like some MPEG-I Frame stuff, DivX or Xvid chances are it is simply not compatible with AE. This has never been any different in the past. You will need to work with Uncompressed files.
Okay let me explain my full problem. As part of some research I need to search through some footage, taken from a submarine, take screen shots and mark down the time I see certain corals so others can go back and try to identify the species ect. On the dvds the files are in the .vob format. For example, on the first disk the footage is broken down into 5 .vob files. The first 4 are about 1 gig (1,042,800 KB to be exact) and the last one is 398,160 KB. If I just play the disk it will of course put them all together automatically as one 2 hour video. I tired to watch the files in VLC player because it's a solid media player and it has built in screen shot capablities however, VLC player messes up the video duration. The video is a little over 2 hours but it shows the duration as :30 for some reason and since I need to mark the time in the video that I took the ss so others can go back to that time that won't cut it. I wanted to use After Effects because it allows you to take a snap shot as well as move the video duration in fractions of seconds giving me superb contorl over my shots assuring I get a very clear one which is helpful since the sub doesn't stay completely still all the time. Being able work with fractions of seconds isn't a must, just nice. So bascially, I need a video player that will show the correct duration and allow me to take screen shots. Playing the video in something like windows media player and then using the print screen key and having to paste the picture into photoshop and crop it would be very annoying with the amount of video I have to go through. Some creative ideas are very welcome. Thanks in advance!