Glitchy Videos/Audio

I am using Articulate Storyline 360. I have a course that includes basic slides with text/audio and some slides with videos.  I've just uploaded the videos from a file on my computer.  They are mp4 videos.  When I preview the course, everything is great.  However, now that I've published it, the videos are very glitchy.  Sometimes they cut off a bit of the audio in the beginning, sometimes they don't play the audio at all, and sometimes I can run through the course and the video that DIDN'T work before, works just fine.  Does anyone have any ideas for me?  I don't think attaching my .story file would help because, like I said, sometimes the videos work and sometimes they don't.  And this only happens after I've published it.  (I've published it for WEB.)  Help is appreciated!  :)