[Keyframe]

Nothing's wrong with infiniband, of course! Except for prices compared to average SoHo network infrastructure. Video mastering and editing networks usually aren't large. You need a fast SAN with fast network and up you go. Everything around it is so expensive though. In recent years there have been a massive price drop in fast storage, fast graphics cards and now we wait for cheap fast networks and 10-bit through and through.

[DiabloD3]

Exactly how fast are we talking? Dual 10gbit nics are now often for $150 + cost of optical modules or DACs.

[Keyframe]

We're talking mastering here. For editing it doesn't matter since it can and is done in proxies. Depending on the bit-depth and fps we're talking anywhere between ~127 MBps to ~253MBps (1+ - 2+ Gbps) per workstation. Usually there are several and a one heavy NAS or several smaller ones. That's for 2K (and HD - but then it's a bit smaller bandwidth). For 4K it's four times that.