How do you get your clips from Xbox dvr when it is blocked from school

The filters are in place for these reasons and are not supposed to be overridden since your computers are owned by your school's administrators/IT can most likely see your history and you could get caught trying to get passed this. I recommend you just doing it on another computer when you get home from school. Sorry I couldn't help...

Note: I have tried to do this my self but got in a lot of trouble so try to avoid doing this.

There are usually legal consequences that can be involved in these kind of situations. The computers are owned by the school or district and bypassing security measures without administrative permission could result in expulsion as well as legal ramifications as mentioned.