As you may know already, I'm a huge Doctor Who Fan. A high quality video of the Doctor Who panel (with Matt and Karen) has popped on youtube! You can find the whole long thing in one part HERE!
Supernatural's panel is also on Youtube. Shot by the same guy who did Doctor Who, you can find it HERE!
The poster, Gonturan74, has many other panels on his youtube page, so check them out, too!