control delete before multiple spaces deletes all those spaces - as well as the following word too
Well, ctrl-delete is delete to end of word, so for sure it eats the word :-)
This is a default keybinding inherited from Scintilla.
due to this, there's no quick way to delete the indenting/aligning spaces
Indents use ctrl-i and ctrl-u.
But aligning using "delete whitespace to next word" might be a useful addition and can be done with a plugin, I think Scintilla has an option to behave as you described, but its simply not the default.
Did you check that none of the plugins in Geany-plugins does it? Addons has many little bits, but there are other plugins that add different things too.
PS don't post videos, if you don't describe what you want people to notice, they may not notice it, and if you describe it there is no point in the video.