If you find your video can't play, or that your video will play but there's no audio, it's almost always because your browser can't play the file's video or audio codec. This is the case with HEVC/H.265 video and AC3 audio, which almost all browsers can't support due to licensing issues. Current state of browser support:
So, if you want animebook to play almost all files, the Woolyss all-codecs+ builds of chromium are your best bet, and you can install Yomichan on it (instructions below). Otherwise your best bet is Chrome, and you'll need to avoid using HEVC video or AC3 audio with it.
Woolyss Chromium installation instructions:
Animebook now supports exporting flashcards to Anki with a Chrome extension. It's meant to work in tandem with Yomichan, so if you're interested, you can download it here.
To use the Animebook Chrome extension,