The video says you didn't see all that was going on. There were projectiles being thrown from the crowd. So the crowd was mostly, but not entirely, peaceful. You are also inaccurate in saying it was tear gas - the park police say it was smoke.
Another point: the crowd was not moved for a phot op. The AG had ordered the block cleared out that morning and specifically wanted the church secured from the crowd that had attempted to burn it the previous night. As much as I wish it was the President who had ordered the block cleared so he could express his solidarity with religious institutions damaged by the mobs, it just did not happen that way.
Granted the police should have found a better way to move the crowd, the point is your rights were not violated. You got to hold your signs and yell your chants two blocks away. No one really has any problem with your peaceful protest whether we agree with it or not. It is your First Amendment Right and in recent days President Trump has made several direct statements of support for your exercise of those rights.
Final point: the President would invoke the Insurrection Act not to stop peaceful protest, but to protect it and also to quell the rioting, arson, and looting that have occurred in several cities. This use of the Insurrection Act is perfectly Constitutional and has numerous precedents.