That there is smoke and interest.
That if or when it does happen, the development would be seen in the stock market as they would have to purchase shares. That's how Glazers did it with us, by buying from larger investors until they made up a majority.
Glazers don't need to give any notice or any heads up as major shareholders if they decided to sell.
I think it's slightly different from when the Glazers took over, not that I have much knowledge of the stocks work and I'm prepared to be wildly wrong/happy to be corrected.
As far as I understand it only a certain percentage of United is publicly traded. The Glazers hold the part that isn't and that's the majority. So even if someone bought all of the shares on the market they wouldn't have control. It's the public float and shares outstanding figures on the left hand column on this page
that shows that status -
https://www.marketwatch.com/investing/stock/Man Utd
It might well be beneficial to start buying up the publicly traded shares first, I don't know. If they or anyone did start buying loads then the prices would go up as you (or them on the vid) said.
I think they could just buy Glazer's shares off them privately too and keep the publicly traded section going. Mind you, that would have to be announced to the market so it would impact the stock that remains too. Prices would almost certainly jump up there too as far as I understand.
Edit: Sorry, my attempts to link to our stock market page has failed. Red Cafe is automatically changing the name of our share listing M A N U (without the spaces) to Man Utd as far as I can tell. I know some people think M A N U is offensive so I'm guessing that's why? To actually see what I was referencing regarding public float and shares outstanding people can type M A N U (without spaces) into the symbol lookup box on that link instead.