drawling an object to a video in photoshop

Okay so as you can see this is a two dimentional animated video of a guy playing a video game trying to take a sip from his drink. Now the object i want in the background is not going to be a triangle of course but im using it as a quick clear example. I want to add an object i drew into this video. But when I drew the triangle it only stayed for a flash second. after 15 seconds into the rest of the video it was gone. I know this was because it was only drawn on one single frame out of the million frames in a video. Is there anyway to select mutiple layors and begin to move the paint brush where each frame you selected now has that object you drew, Otherwise i just dont see the point of editing videos in photoshop when you could just edit in after effects. When i found out photoshop could now edit videos i thought wow! this could be great but if i have to select each frame indidivually and re drawl or copy and paste what i drew in the first frame just for it to be there for the whole video then its not worth it. could someone please help me out?