I have several memory cards (SD) in use with my Nex-5 but I do not know if these cards are also suitable for use with the Nex-5 movie option. The cards that I have: 16GB SanDisk Ultra Class 4 and Class 4 16GB Sandisk VideoHD. These are 15MB / s. I doubt if I should switch to the Class 6 ExtremeHD Video (20mb / s) So far I have only made short films and thus no problems detected. But I do not know if it makes a difference with longer movies or burst shooting. Class 4 cards would then also be sufficient?