Sony Choice of Memory Cards

I have several memory cards (SD) 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?
I think what I've read is Class 4 is the absolute minimum but I agree with bilsmale, the feedback I've received from others is at least Class 6 or higher. I personally go for Class 10 just to be on the safe side, even if it's overkill.


Agree with everyone. Technically, Class 4 should be sufficient. I went with a Trascend Class 10 to be safe.