You can watch the previews after the jump. Keep your eyes peeled for Bale's bongo stylings at the 1:20 mark of the Hustle preview and at 19 seconds into the one for Furnace.
The two previews employ Bale's mannerism for different effect. In Hustle, Bale bongos upon the caboose of an unidentified woman who's crouching on his desk—an image of base-level sleaze (or is it presexual curiosity about the body as object?) amid sophistication and wealth. (The movie is evidently about a successful art forgery operation.) In the Furnace preview, Bale, playing a factory worker this time, performs the gesture on the roof of his car after meeting up with a character played by Casey Affleck. The bit of dialogue in the previous shot ("Wooo!" "Oh my God! Man!") implies that these two are eager to spend time with each other, which brings a sense of urgency to the tapping.
Bale is a fine actor, and I expect I'll enjoy seeing him in both films when I watch them in their entirety. Yet seeing him do the same thing in such different contexts (and in such close proximity) made me briefly skeptical of his talent. How shrewd a piece of Method-style shorthand it seemed, a sign for both gracelessness and pent-up nervous energy.
I suspect this has less to do with Bale than with the lousiness of most recent coming attractions, which encourage a sense of smug superiority by reducing any film to a collection of familiar moments. The visual shorthand of Hollywood previews can make even the most original new movie look like something we've seen many times before. (Steven Soderbergh offered a compelling explanation for this in the interviews he gave earlier this year to explain why he's done making feature films.) Perhaps Bale simply likes bongoing on stuff. If so, perhaps he'll find a way to combine that enthusiasm with a sense of sophistication (or at least rhythm) and one day star in that fictionalized remake of Buena Vista Social Club the world's been waiting for.