Conductivity and high speed transmission using aluminium slip rings
You can send video frequencies through a slipring without trouble. Maybe more if you use LVDS and the arrangement is symmetrical enough. You can get commercial sliprings for a reasonable price, from China for example. 

However the operating lifetime might only be a few hundred hours for that sort of thing. 

I believe the heads in VCRs used a rotary transformer for the signals and did not use sliprings at all.