Basic question - is it normal (gut says no) for the entire machine to flash when flippers and bumpers are engaged? Assuming not, what could be the cause?

Video example

As an FYI, the back glass and playfield bumpers are LEDs, the remaining playfield lights are incandescent. The flashing is not specific to either bulb type - it happens to the whole machine. Also, in case it's a fuse-related thing, the 15 amp 30v fuse has been recently replaced, the 1 amp 'slo blo', 10 amp 115v, and both 10 amp 6v fuses are the ones that came with the machine (i.e., I don't know how old they are).

When playing, it comes across as possibly intentional as if it is adding to the gameplay....but my gut tells me that there is something being strained that I should replace. Your perspectives are appreciated!

The video doesn't do justice to how noticeable it is that the lights are essentially turning off/flashing when the bumpers and flippers are activated. You can see the flicker a little bit in the video, but to the naked eye it's much more noticeable. I adjusted the YouTube video to HD playback and it was a bit easier to see when it happens. Again, this isn't negatively affecting my gameplay, I'm just curious if it points to an issue that I could fix.

I should have clarified that the blinking occurred when I got the machine initially (with all incandescent bulbs).

Thank you...I'll start hunting down these relays and see what I find!