Well, zoom mode just isn't the universal answer and the OP is clearly looking to expand his horizon. I understand you want to try to promote Siglent as this is the brand you sell, but realistically it doesn't hurt to try / investigate various pieces of equipment from various brands to see what would be a good fit. That is exactly what I do when I look for a new piece of equipment.
"Zoom out" is term related to using zoom function. Nobody cares about "changing timebase after the stopped capture" except people that don't know how to set timebase right in the first place.
He can also ignore sensationalistic clickbait video and, as you point astutely, think with his own head, and decide not to use scope wrongly...
I wholeheartedly agree with you he should try and use real data and make a decision on his own.
I use several Siglent scopes and a Keysight pretty much on daily basis. Out of reasons where I use Keysight instead of my Siglents, there are some decodes and some other stuff that is more suited for the task, but relying on the scope to capture stuff outside of what I set it for by chance to cover my bad practice is not one of them.
Like I documented few times before, Keysight DOES NOT capture outside the screen. What it does is cheat. When in RUN only screen length is captured. If you then press STOP, it performs a separate, additional, new trigger where it captures long.
It performs this: it changes timebase to as long as it can (cannot say long because it has 100x less memory than this inexpensive Siglent), takes Single, waits for trigger, captures and goes back to timebase it was on.
If there is no trigger for some time (cca 200-250ms timeout), it will timeout and show you last good triggered capture, that will be only one screen wide.
That video was proven factually incorrect on many points.
Whoever uses that one to make decision is making a mistake.
This imaginary "this scope knows better than you and has captured data you would otherwise miss" was proven to be false argument.
It should not be used as a criteria to chose a scope.
If for some reason you need manual memory control, that might be valid checkpoint, OTOH. I can understand that.
But more important is manual control of sample rate. That is used all the time. And that is there.
And as Josh rightly said, is there really anything better than SDS800xHD in that price range?