I have watched them more than once and tend now to visualize the episodes on my own.
And this is the reason I recently picked up the comic book collection on DVD-ROM of 500 Trek comic books
including many from the TOS series characters on the various Enterprises.
and also picked up a miniseries comic from one of the original writers on TOS, D.C. Fontana:
Star Trek Year Four: The Enterprise Experiment
While I've actually been busy to sit down to read them since getting them I have skimmed through them...
I can visualize them myself from the drawings. Maybe put on some Trek movie soundtrack to get in the mood...