I wonder if the lack of audience enthusiasm (besides all of the good points listed above) also has something to do with the fact that the band are lip syncing and "miming" to the studio recording of these songs--the audio is clearly the studio recording and not live audio. Lip syncing/miming to the original studio recording wasn't an uncommon practice on these types of shows in the 60's. I have DVD's of other 60's bands (like the Moody Blues for example) on shows like this one lip syncing/miming to studio recordings in front of a live audience.
Lip syncing also killed a lot of bands' enthusiasm in studio performances too.

If you like LIVE vintage vids, search "old grey whistle test" or OGWT, a fairly endless supply of good stuff there.

For instance this performance of "Badge" by Clapton. I'm not a huge Clapton fan, but this is a great rendition, and i kinda like that lefternmost back up singer too!

ERIC CLAPTON - Badge (1977 OGWT UK TV Performance - but quoted as 1974) ~ HIGH QUALITY HQ ~ - YouTube