I finally found the time to put together two basic tutorial videos for hexcap. They're embedded below, but the quality is definitely better if you watch them directly on Youtube.
The first is a brief introduction to basic packet editing in hexcap.
The second offers some basic instruction in how to transmit and receive packets in hexcap.
As always, check the man page for more complete descriptions of functionality. The plan now is to make a third video explaining generators and masks.