Unfortunately, converting videos to MKV is not an option anymore. The game has been built with AVI videos, so changing the extension means importing the videos again in each scene. There are too many of them so we have to continue with AVI.
You can replace the file paths directly in the ved-file in a text-editor, e.g. replace ".avi" with ".mkv". Then write a script to convert all your avi files to mkv with the right codec. This shouldn't be too hard.
However, I think the encoding is not the problem. In Catyph, I have AVI videos in Xvid too, and everything works well. There is a video between each scene, and the game doesn't crash. So the AVI/Xvid videos are possible and I think it's an issue to be found in ASA only.
I think it's very likely that the video is the reason for the crash. And AVI is just a container format, there are many different codecs (for video and audio) with different settings.