A Washington Post video reported that China’s Alibaba is preparing to make a bid for all of Yahoo. The Chinese e-commerce company, run by Jack Ma, has long wanted to buy back the 40 percent stake that Yahoo owns in it. The bid, for $20 a share, would value the venerable search engine at $25 billion. Eric Jackson, a major Yahoo shareholder and founder of Ironfire Capital LLC, thinks that price is too low. If that name sounds familiar, it’s because Jackson let an investor revolt back in 2007 that led to a change in the CEO. But despite his reservation about the low price, in the video, Jackson n…