Indeed if someone could 0wn your box simply from you watching a stream of a talk at a conference, it would already have happened.
The bigger risk is IMHO to end up on someone's watchlist, especially if the country you live in isn't particularly respectful of your individual freedom.
There's no doubt that I already am on a watchlist in the USA. Most anybody who's given talks at hacker cons, and then approached by the mil side of govt is. And frankly, I don't care.
Hacker con sec can be boiled down to 2 simple principles: Update yo shit, and if you have access turned on (ssh, etc) to know their threat model.
Well, yeah. But the US progression to being on a watchlist is a (metaphoric) white van for more watching. Other countries get you a (metaphoric) black van that takes you somewhere unpleasant.
The bigger risk is IMHO to end up on someone's watchlist, especially if the country you live in isn't particularly respectful of your individual freedom.