So, I recently saw a video on youtube of Alicia Markova performing Giselle and I completely fell in love with it. So I was wondering if anyone knew if there is any videos (of full length performances or at least documentaries or anything else) that feature this wonderful ballerina.

i'm not sure if this is available commercially, but a number of Dominique Delouche films are, in which case you might look for Delouche's 2001 film "Markova, la Legende." it contains clips of the ballerina at work in coaching sessions and also includes films of the ballerina in her prime, GISELLE may be among them, if mem. serves.
as far as release of the several films made and telecast in the UK - LES SYLPHIDES and GISELLE, for example - i've heard of no intentions toward putting these on the commercial market.
the current NYPL exhibit about Diaghilev, includes an excerpt from the SYLPHIDES kinescope - w/ Karsavina introducing the filmed ballet led by Markova, Violetta Elvin, Svetlana Beriosova and John Field.

the credits to the NYPL vid selection is as follows:
Les Sylphides
(excerpt introduced by Tamara Karsavina)
Choreography: Michel Fokine; corps de ballet rehearsed by Lydia Sokolova
Music: Frédéric Chopin
Scenery: Richard Greenough
Cast: Alicia Markova, Violetta Elvin, Svetlana Beriosova, John Field, and ensemble
Artistic advisor: Cyril W. Beaumont
BBC-TV, produced and directed by Christian Simpson, 1953.

Ballet fan, I know Markova only by reputation but have been reading about her recently. Like you, I'm curious to see her on video and film.

One thing to look for in the videos is the date. During World War II, when Markova danced in NYC with Ballet Theater, she was considered by the major critic Edwin Denby to be the most important ballerina dancing in the United States.

As early as 1945, however, Denby began recording a certain lack of strength reflected in reduced "vitality, "understating the climaxes," though not yet a decline in her jumps. ("It is as though a singer were to get the mannerism of taking fortissimos in half-voice, a kind of crooning in ballet.")

By 1952, when she returned to Ballet Theater for Giselle, the Met was standing-room only. Denby reports:

Let's hope there are earlier videos available so we can see Markova at her best.

This quote is so interesting. I do can relate to that feeling, having seen just a replica of the above in Alonso's last years. But there was certainly something fascinating in the way this things were done, how calculated were the cuts, how brilliant the elisions became or how puffy and big the romantic tutus were designed to serve this purposes. The camouflaging didn't look as just the mere basic desire to trick the audience. As we all know, a knowledgabe public gets hardly impossible to lie to. At the point where the absence of former vitality and strenght becomes obvious for both the dancer and her aoudience, this is also a unique opportunity for the ballerina to reveal that other side that only comes from years onstage: maturity, artistry and a good dose of histrionism and acting skills, things that are sometimes quite hard to find in vigorous starlets. In other words, the lacking gets replaced, and the final result is a solid sense of balance.
I too would LOVE to see more of Markova's younger years. I have all her Giselle excerpts with Dolin in a DVD, downloaded from Youtube, along with Spessittseva's, Alonso's, Fracci's, Ulanova's, Chauvire's and now lovely Kirkland's.

Christian---you write of Alonso's last years---when she was in her 50's and 60's? The Markova Denby is writing about is 35 years old. supposedly in her prime (she was born in 1910). It is not a fair comparison