Video audition memory limit tips? Strategies to fit the audition into memory limits

Trying to figure out the best way to film DS violin auditions. Limit for schools vary but 250mb seems typical. We have a reasonably nice microphone and webcam using the laptop but filming with cellphone sounds better when we listen (but needs to be compressed). I searched this forum but has anyone come up with the best way to film these auditions to meet the memory limits?