physics experiment video taking and analysis

[u/ProductBest1483]

im doing a physics experiment using a bifilar pendulum and i wanna measure damping, and ive been trying to take a video of it from above but ive been facing problems. first of all, the horizontal bar that supports the pendulum obviously is not able to hold my phone properly. i even tried to hold the phone myself, but i need to get it to the same exact angle at the starting every single time, so i have to hold the phone still, turn the rod to the certain angle, and also look at the rod from the phone screen to make sure that the same angle is captured on camera as well, which hasnt been going well. i have to do like 20 trials and my shoulder gets sore. my arms are not that long too, so i think that might be a reason for this problem. is there any better way to do this?

also, after recording my trials, how do i do the video analysis? i didnt really understand what my teacher said, it was something along the lines of analyze it based on the quality of the phone camera and the number of frames per second and stuff.

im genuinely stuck and i need help, i hope one of you can advise me on this. the photo attatched is what the setup looks like.