I had no idea — the presidential candidates of the two major parties have collectively posted 2,434 videos on YouTube. (Mitt Romney leads the pack with 436 videos, and nobody’s a close second.) Here’s why I didn’t: like almost everyone else, I’m not paying any attention to them.  “Over a two-month period, a viewership of less than 1,000 people [per video] is often the norm,” reports my friend Scott Jacobs on theweekbehind.com, where, as “Stump Connolly,” he posts his intriguing political commentary. Mainstream coverage still matters most, Jacobs writes, and as always, it’s driven by the pollsters. And when the pollsters call, says Jacobs, “none of us, I guarantee you, will say I like Candidate X because he had a really great video on YouTube.”