When I upload a video from my Android to my dropbox account it deletes or won't play the first 10 seconds of my recording. Yet, interestingly, both the recording on my Android and the recording on Dropbox are the same length (12 minutes, 10 seconds). Strange. It does it on every recording now, and didn't do it historically. When I leave some empty airspace in the recording, it skips that and still cuts the first seconds of my MP4 recording. Since these are professional pieces for work, it renders them useless because they lack a professional intro statement, thus rendering Dropbox pretty much useless for my work.
Is it possible that it's an issue with the video player rather than the files themselves? In other words, if you open the files on a PC or with a different video player, does the same issue still occur?