It's not exactly "practice," but you can play the Best of Putting CTTH as an option. They're all pretty lengthy putts with decent breaks, so you won't be able to work on those 10 & 12 footers, but at least it doesn't take any life off of your balls.
And the only way to watch others play is if they live stream their round, or record it so others can view the video later on.
Happy New Year - Kelsey =)