what's the best way to make a clear recording of a commentary for my movie |
Plug a mic into the mic connection of your PC and record. If you don't have a decent mic and a noisy PC, record to an external source away from your PC, then transfer.
what's the best way to sync it with the video |
Watch it as you talk

Start the recording at timecode xx

x

x, amd drop in the timeline at xx

x

x.
and make it an alternate audio track for my DVD |
Make sure your DVD authoring software has the facility for this by reading the manual