All kinds of video conversion software can do it. There are plenty of them out there (as long as the software can convert video files format). In fact, your request itself is a recoding process. But I must warn you: If you feel that the file is too large, and want to reduce the bit rate of reducing the volume, please note that an experiment, see clear is not clear whether meet your requirements, then all transformation (only refers to the same film, another you need to repeat this kind of method to find the appropriate bit rate) if you are too now video files or sound quality is bad, want to improve clarity, etc., I advise you not to waste effort, impossible to achieve, the only result is to increase the size of the file.
BTW, if you come across some YouTube playback error. You can also check this article where I found this solution to YouTube playback errors.
