Short-form video took center stage at tech and social media companies’ annual presentations to advertisers, as platforms like Snap and Meta look to capitalize on TikTok’s political uncertainty in the U.S. to take ad dollars from their rival.The presentations in New York, known as the NewFronts, come just a week after U.S. President Joe Biden signed a bill that gives Chinese tech company ByteDance up to one year to divest TikTok, or else the app…