Is faster video rate better than slow video for live streaming of thermal images?

Yes, slow video (7.5 fps or 8.3 fps) is accomplished in the Tau2, Quark2, Muon, FLIR Vue, and FLIR Vue Pro by replicating (not averaging) 4 or 3 frames, respectively.

    30 fps divided by 4 = 7.5 fps     25 fps divided by 3 = 8.33 fps

This is the method by which FLIR complies with the requirement that slow video be less than 9 fps in order to export FLIR's thermal imaging cameras without an export license.