For me:
RLM Audio stream is 20secs behind live,
RLM Studio vision is 25 secs behind live,
and Eurosport Player's feed is 30 secs behind live.
So thankfully it's not too difficult to sync up for me, although YouTube's live player has a habit of removing any delay you've put in the video every few secs, which is annoying

Sadly that's out of RLM's hands of course as it seems to be a quirk with their live player.
I know they say that "We're not a video service" etc. etc. but I do feel that it's just wrong to watch Le Mans without their commentary synced up, and I much prefer them to the other commentators (Both Eurosport & World Feed). And I think in the race they do commentate on what's happening on the TV feed more.
I suggested to them on Twitter that they could have a video feed that's literally just the session clock (plus their audio), which would save on bandwidth vs the normal studio-vision channel (As while they route the regular Audio feed through more reliable methods to their website, the youtube feed was going via satellite internet, which was dropping out cos of the rain - if you're just sending video of a clock, rather than a proper webcam feed, then the bandwidth needed can be much lower), for those that just want to sync RLM with the TV feed, but they weren't having any of it :/