How does Trump do character stat graphics on screen?
This video has had post-processing done by his YouTube video editor, Jenz. Trump's fanbase often express great appreciation for these edits because they are very informative and are often complex and context-specific. The example you give is one of these edits.
However, Trump does use Hearthstone Deck Tracker onscreen for his decks so viewers know his decklist (and so he can quickly know which cards he hasn't drawn yet). For his arena picks, he has recently started using ArenaTracker to compare card quality "rankings" between HearthArena and Light Forge (though HearthArena was recently removed because of an API change). These two tools provide some of the visuals, but everything else is edited in by Jenz.