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Create a file, move it over, delete the file, rinse and repeat.
100mb files are still pretty large, at least for internet transfer they are.

Hanging with no exception could indicate an infinite loop or some sort of waiting.

Are you able to provide us with the console output? You have print statements in your code. That console output...

As a final check, yes. But while uploading, you will probably find that exceptions are thrown if there are any issues (perhaps connection exceptions or something). Catch these exceptions, and do...

When you remember that all files are just long lists of bytes (including media files), anything is possible, lol.
Don't get caught up on the idea of a file having some sort of extension which makes...