Well firstly you'll need to do a lot of converting.
Secondly, Are the videos short or long. Is it a video app or a game with cutscenes. Reason for asking this is that videos tend to take up space, therefore it'll probably be very large.
There is a video plugin:
and the author also talked about offline video too.
Since HTML5 only supports a limited number of video formats, you'll have to convert them (as mentioned before). I haven't quite used this plugin (yet) so I can't really say for sure if it is what you are looking for.