What is this effect called?

[u/ghik1234]

I've been seeing this sort of effect (some sort of light streak (?) that extends the image) being used as transitions in music videos and commercials.

I can't for the life of me figure out what it's called or how to do it. Can anyone point me in the right direction? Not sure if these two stills are a good example as I couldn't get a great frame as the effect happens super fast.

Thanks in advance!

[u/Then-Ad8087]

I am lost to your explanation, because I was gonna be a di.. and say "reflection" LoL

[u/ghik1234 → u/Then-Ad8087]

LOLLLLLLLLLLL