When I was looking for footage from the Dumont Networks' "Mary Kay and
Johnny," the first TV show to feature a married couple sharing a bed
(brilliantly researched for me by researcher Pinkfreud), the path led
to NBC, which owns the copyright, as well as many other Dumont
programs. I'm not sure they own them all, though.
Here's a fast way to find out what you want to know about specific Dumont shows:
First, use IMDB.COM (Internet Movie Data Base). Type in the name of
the show you're looking for and
on the right hand side will come up an Amazon box telling you whether
it exists on DVD or not.
While you're on the iIMDB entry, on the column on the left, click on
"Company Credits." The new page will list the production companies
and distributors and years of ownership.
IMDB is often wrong, though, with incorrect or incomplete info. So
another invaluable source is the MUSEUM OF TELEVISION & RADIO. Their
reference librarians/consultants are super nice and helpful.
If they don't have the copyright holder info, they'll track it down
for you. You can also go there in person and watch old TV shows and
listen to old radio shows. (And new ones, too).
I only know the New York branch (there's also one in LA).
Here's the contact info for a reference librarian:
Tuesdays to Fridays, from 4:00 to 5:45 p.m. (EST) only, call
212.621.6600, press "0" to speak to an operator, and ask for the
library; OR e-mail LAreference@mtr.org."
Since you mentioned Ted Mack's Amateur Hour, just for the hell of it,
I looked it up on IMDB.
The Amazon box shows that it IS available on DVD, distributed by SRO.
(Standing Room Only.)
The "Company Credits" list it as owned by Dumont, CBS and NBC . . . so
this would be one of those times you'd want to verify with the Museum
of TV & Radio. . .depending on which year(s) you were interested in.