Next to the footage of Glen with The Champs, http://www.historicfilms.com
has some more footage with Glen available online. Just search that website using "Glen Campbell" as search term.
I think the most interesting clip, next to the one with The Champs, is about the inauguration of Ronald Reagan in 1981. So not only did Glen sing during the 1980 Republican National Convention, performing the National Anthem with Tanya Tucker, but he also was present at Ronald Reagan's inauguration, on January 19th, 1981.http://www.historicfilms.com/tapes/636
I'm a carefree, range ridin', driftin' cowpoke...