Sorry, at YVR there is no bypass that I am aware of when coming FROM the US, transiting to Asia or another area.
I think they do have to clear Canada customs, and then re-check their bags to continue on to their final destination. I've seen them queue up in line each time so I'd be surprised if there was any bypass for this.
On the way back though, there sometimes is a Canada Customs bypass when transiting TO the US (seems to be open part of the time).