pynetworktables has a latency of up to 50ms, and isn't designed for streaming data. NetworkTables3 (which pynetworktables does not support) ... might have support for that? But, probably not.
The HTTP approach would be best. I might get to something like that later in the season...
We had a crappy non-http server implementation that we prototyped last year.
https://github.com/frc1418/2015-visi...chpad/rio-mjpg