Increase success rate by adding back to queue the "timeout" videos

[rom1504]

[pabl0]

This would be nice, but I think even a simple retry would help in many cases. At least with some datasets served from a CDN it seems sometimes a download gets stuck but the next attempt works just fine (when just simulating by downloading the same file over and over with wget).

Currently the tool only supports retrying whole shards, right? Img2dataset let's you retry single files, too.