JPEG 2000 for each frame? I wonder what they use for decompression. JPEG 2000 decompressors are really slow. Most couldn't keep up with frame rate without GPU support.
Dedicated hardware, not even regular GPUs. JPEG2000 decompression has a rather complex entropy decoding part which is not easily parallisable.
Only on the intraframe level - Frames are independent so overall it's "embarrassingly parallel".
There's no point to decoding in parallel if you're watching in sequence.
If your hardware can only manage 4 frames per second but you need 48, then decoding with 12 sets of hardware in parallel achieves your goal.