Although not exactly dedicated to guitar, I thought that this might be of interest. It's a Radio 2 four part documentry about improvisation. It's more about the mentality and ethos behind understanding and creating. Beginner friendly as well.
You've only got around 24 hours left to listen to Part one as it will be replaced by Part two on Tuesday night (15th March - Weekly updates)
Main programme description:
If you can't open the dedicated player from there try here (Replace ** with tt copy & paste link):
"Sometimes you want to give up the guitar, you'll hate the guitar. But if you stick with it, you're gonna be rewarded." Jimi Hendrix.
thats pretty cool. 8)
Stairway to Freebird!