To ensure that the files are actually are downloaded (step1), before deleting the original (step2). I would make make step1 an input to step2. That is step2 cannot work without step1. Something like:

    (step1) Download video from URL.  Include the Id in the filename.
    (step2) Grab the list of files that have been downloaded and parse to get the Id.  Using the Id, delete the original file.