As a former Blockbuster employee (god, those dreaded days).. I'll field this. Yeah. They do have Blockbusters in Canada.. They have them in pretty much every country anymore (ahhh, corporations).
However, I do believe this giftcards are on a different system then the ones in the U.S. I wouldn't risk it if you just plan to straight buy them. On the website they have a statement in the 'about' section that says "can be used at bleah bleah.. In the United States." The Canadian website has a similar disclaimer.. bleah bleah 'any Blockbuster in Canada."
Here's the US One:
GiftCards
Your use of a BLOCKBUSTER GiftCard constitutes your acceptance of these terms as well as any additional terms printed on the GiftCard package. BLOCKBUSTER GiftCards may be applied toward the cost of any product sold or rented at any participating BLOCKBUSTER store location
located in the United States up to the remaining value, except that GiftCards cannot be used to purchase GiftCards. Membership rules apply for rental. GiftCards are not redeemable for cash, may not be returned and will not be replaced if lost or stolen. After 24 months of non-use of a GiftCard, a monthly service fee of $2 will be charged per month against any remaining positive balance on the GiftCard commencing on or about the first day of the 25th month, until the GiftCard balance is zero ($0). Monthly service fee void in CA, MA, NH and where prohibited by law. For BLOCKBUSTER store locations, please visit our website at
www.blockbuster.com.
I'd imagine there is some crossover in say.. Vancouver.. but if you're going off the boarder, I wouldn't risk it.