They had previously arranged to lead the parade, then when given the opportunity, they held everything up most of the way down the parade route - apparently for the better part of an hour, until a Pride official signed a list of demands.

CBC coverage

Toronto Star coverage, with a strange title/lede incongruity. Seems they were planning to run a puff piece and this event was rather inconvenient for them. Here they are on Twitter.

/r/toronto thread, of course. Surprisingly little drama, few people supporting BLM.

The list of demands, apparently. I saw other sources claim the funding demand for "Blockorama" was in fact 13k rather than 10k. Moar.

Statement from BLM, apparently.