Okay, so I've watched the "City under siege" video - I found it entertaining and it kept me on for the whole 55 min. of the show. The soldiers are still shapeless blobs of colour, but the commentators were competent and quick to react. They went "here's the kerns" and "these are heavy archers" - so not being able to discern the unit types wasn't a show breaker anymore. Camera handling and movement was good. The camera presence problem - you can't be everywhere at once - was alleviated by the fact that the battles were sieges so most of the action took place in the central plaza ; they also had a second camera set up for action outside the walls.
As a bonus, the guys doing the comments were funny too ("Do it, pilgrim ! Do it !") - they gave me few laughs along the way...
So, live TW may not be such a bad idea after all... but still, I'd like to see some way of presenting it that's more appropriate to this kind of game - classic TV show style doesn't really cut it.