The Collegiate Shag ... originated in the South (possibly New Orleans) and has been known at times as the "Flea Hop" (not just the Dance variation flea-hop.) The Shag was popular in the late 1920's and supposedly predates the Lindy Hop with the collage students. It was primarily danced to fast Ragtime - Jazz type music. There were many Intercollegiate Dance Contests held in NYC in the 1920s-1930's which held a "Collegiate Shag Division, Conklin and Coleman won this type of division. Virginia Beach was a hot spot for the Collegiate shag as some eastern cities banned the dance as well.
Over the years this Shag has split a few times into the various forms. The Collegiate and Murray Shag (seen in the clip) can be mixed with basic swing patterns and the Jig Trot and thus becomes a frantic type of "Swing Bal" (See Balboa.) The Carolina Shag is said to be an offshoot of the Collegiate Shag and Charleston in the 1930's but is more of a Swing dance form than a Shag dance form today. The Saint Louis Shag is more of a speed dominated/ competition shag, which is different than the Collegiate, Carolina and Murray Shags. The Balboa (uses the 8 count of Lindy) was somewhat a more subdued smoother variation of the Collegiate shag (uses only the 6 count), and swing, which still shares some similarities today. All dances have extended rhythms (counts) beyond the basic.
The Collegiate Shag is its own dance like the Charleston, Black Bottom, Balboa etc. that can be danced separately or interwoven into swing. It is however a part of the swing dance family of dances, however it is not a swing dance, but rather a companion dance to swing like the Charleston, Fox-Trot, Suzy-Q, Balboa, Big Apple, Little Apple, Truckin, Black Bottom etc. When the dance is interwoven it
does however have the look and feel of Swing dancing, but different.
It was somewhat popular today with some Retro-Swing dancers in Southern California in the late 1990's and is very cool looking with its Slow-Slow-Quick-Quick rhythm with fast hops and kicks and closed contact to your partner is a blast to do.
Note: A interesting thing in Arthur Murray's 1937 Let's Dance book, he breaks it down as a Hop-Hop-123 (kicking on 3) but breaks it down differently in his video. The Movie Swing, Swing, Swing has a good musical short of this dance.
I ran across this gentleman's Video (on left) on Youtube and thought it was really good and fit this page well.