clean up tmp file

[blshkv]

Fixes #135

Context

Keep FS clean

[time4tea]

Hi. I appreciate the effort here... but the proposed solution ignores the reason that the file is kept... which is to be able to review the ffmpeg file after the creation of the video....

By deleting it, it can no longer be viewed...

There are a number er of considerations that need to be balanced here, and currently the one that seems to work, is just leave the file.

Do you have a particular reason you need the file removed, or is it just for correctness? If I understand your issue it may help in coming up with a useful solution.

[blshkv]

hm... The purpose was just to delete a random tmp file. My /tmp directory is a RAM, and I don't reboot my machine very often, it is getting polluted by some leftovers like that one.
I didn't expect that a user would be able to find it, or it could be useful in any way.
But I see, you want to keep it as a log file. Wouldn't be better to have a prefix at least, something like: "/tmp/gopro-dash_<random>" ?

tempfile.mkstemp(prefix=source.name...