Rep. Gabrielle Giffords’ official YouTube account is subscribed to her suspected shooter’s, though it’s unclear when this occurred, who did the subscribing, or why.
On YouTube if you subscribe to someone’s channel, you are “notified of new videos from this channel.”
Currently Giffords’ channel is subscribed to suspected shooter Jared Lee Loughner’s page, though it could very well be that this occurred since the shooting, not before. Her page’s only other subscription is to Rep. Ike Skelton’s channel.