That video is aimed at cheaper USB scopes. Picoscopes shouldn't be lumped in the same category.
I've not used one but I did investigate them before choosing to buy a different scope.
The pros are :
i.) small and portable.
ii.) generally lower cost for a given spec (though the cheap Chinese scopes perhaps are cheaper).
iii.) very good software support which doesn't cost extra and is upgraded (e.g. various serial decodes)
iv.) large display via a computer monitor
The cons are :
i.) low voltage (maximum is around 20V I think)
ii.) grounding depends on the grounding of your USB connection which might not be what you want
iii.) less convenient to use - people generally seem to find USB scopes a pain to use in terms of having to set things up with a keyboard and mouse rather
than twiddling knobs on a real scope
iv) the sampling rates are a little low on some of them (the headline rate is shared - check the specs carefully)
I've probably left a few out, but I'd say don't dismiss them out of hand but make sure you have looked properly at cheap DSO options such as Rigol or the option of an
analogue scope as Dave says in his video though if you're short of space (as I am) an analogue scope is quite large and takes up much more space than modern digital
devices.