added .jpg to extensions to be deleted
added -f flag to mv command to ensure files moved to destination do not fail due to existing target file
renamed variable "dirname" to ensure it does not interfere with the call out to "dirname" when getting parentdir added logic to the move section to check the file sizes. if a larger (720p) mp4 file exists at the target location already, then assume we want to keep the newer smaller non-720p mp4 just downloaded.  Therefore force an overwrite during move.  Otherwise take no action.
changed clean-up files find command. -regexp to -iregexp for case-insensitive. regex syntax change to extensions