If you encounter any problem I'd like to know. Here are some things you can try yourself if you prefer.
By default vcs uses FFmpeg to process the video. If it fails, MPlayer might work better.
Use -M to try using MPlayer.
Use -F to try using FFmpeg (this is the default, running without arguments is the same).
The only exception to this is the DVD or ISO mode, which can only work with MPlayer.
By default error output is suppressed when calling FFmpeg or MPlayer.
Player errors can be displayed by overriding stderr and/or stdout:
$ vcs -O stderr=/dev/stderr -O stdout=/dev/stdout [options] file.avi
Will display errors on the same console you're running vcs.
$ vcs -O stderr=stderr.txt [options] file.avi
Will save error output to stderr.txt