Television critic Tom Shales of the Washington Post used "begathon in 1978, but Newsday is not fully digitized for easy searching.
A multi-day event on public television, used to raise money so
you won't have to watch commercials.
(Google Books) (full text not available)
The Second Barnhart Dictionary of New English
by Clarence L. Barnhart, Sol Steinmetz - 1980 - 520 pages
15 July 1974, Chicago Tribune, pg. 16:
DOWNERS GROVE -- After watching the recent Democratic "Beg-athon," it wasn't difficult to determine where the philosophy came for George McGovern's statement of "Crawling to Hanoi to achieve peace."
A. D. Vinikour
19 March 1978, Washington Post, pg. F1:
The Marathon Begathon
What's More Dignified Than Pitching
For Bucks on Public Television?
9 December 1979, Washington Post, "Pay or Be Dumb: The Marathon Begathon" by Tom Shales, pg. A1(?):
In honor of public television's current -- and umpty-umpth -- fund raising membership drive, we present a rerun of our own: "Pay or Be Dumb: The Marathon Begathon," first published in March 1978. Little revision has been necessary because nothing much has changed.
17 August 1983, Chicago Tribune, pg. D9:
Both stations -- well versed in the annual fundraising "begathon" -- had telephone banks in place for clients seeking only audio conferencing.