TIL that some galaxies, even if they’re far (ex. M104) has better live view through telescope, compared to closer ones, like Andromeda – why is that?

So, I saw a post on Instagram, showing live view of M104’s whole disc from telescope, but it looked like some editing was going on. Then I went to YouTube to confirm the same, and found that it’s indeed true.

Here’s the video:

Can somebody explain the science behind this? I always thought that only the core is visible in most galaxies’ live view.