• A lot of effort has been invested in Video DownloadHelper. As a result, this add-on is a very solid piece of work.
• It has *never* crashed.
• Converts from almost any format to one you like, with consistent results.
• The need for a support call never arose but the developers seem to be pretty decent folk.

If you can't decide which video download tool to use, you can't go wrong with this one.