Research - How Base-Tracks Work

Attempting to recap on my music video made before the summer in AS is proving to be a challenge - I can't find my video on the blogspot (Though my digipack's on there). However, I can remember the filming process; We filmed two base-tracks: A wide shot of me and my other two partners: Kellie & Deborah dancing, and a close-up tracking shot of us three again, but standing still side-by-side. Though I've got the gist of base-tracks, I'm still unsure of markers. I believe we used this to sync audio from the song with Kellie (the lead actress)'s facial movement. On the other hand, most of our video was choreographed dance so there were very few shots in which Kellie was caught singing. In all honesty,  markers is something I'm going to need to work on before filming my A2 video. 
Because I couldn't find our own cut of the video, I thought I'd post Madonna's original video. Perhaps you could feel sympathetic for me when you see the dodgy choreographed dance-scenes!