Unfortunately, Biden is speaking in very cryptic terms.

This COULD be interpreted as saying:  "If Trump starts looking into the details of your finances, you're going to end up in big trouble with Trump."  YOUR economic and physical security COULD be a reference to those of Ukraine, rather than him personally.  Biden is very obviously and deliberately using cryptic and ambiguous language.  You can hear him pausing to think of the right way to say it without exposing something.  And this 2016 Biden does seem to be very much more lucid than the 2020 Biden.  If wonder if sometime between 2016-2020 he didn't suffer some kind of medical event, perhaps another stroke, since there appears to be a rapid deterioration between 2016 and 2020.  It does SOUND like a threat (whether to him personally or to Ukraine is unclear to me), but it could also be a warning to the effect that, "If Trump finds out, you'll pay the price."