This video from Britain says about itself:
12 April 2011
This bird ID video gives useful tips on how to distinguish between Willow Warbler and Chiffchaff. It is one of a series of bird ID videos produced by the BTO. To see more videos giving help with tricky bird IDs visit www.bto.org/about-birds/bird-id
This video says about itself:
20 April 2011
In the second of our series of videos aimed at helping with the tricky task of identifying warblers, we take a look at Blackcap and Garden Warbler. BirdTrack reports show that Blackcaps are now here in significant numbers and garden warblers are just arriving so it’s a good time to brush up on the songs and ID features of these two common species.
Birds in Britain: here.