(Quotes from witnesses, victims and officials) Feb 18 (Reuters) - At a grilling by lawmakers over the frenzied trading in retailer GameStop, Keith Gill, a YouTube streamer known as Roaring Kitty, hedge fund managers and the head of Robinhood and Reddit defended their actions. Those testifying were Robinhood CEO Vlad  Tenev, Melvin Capital CEO Gabriel  Plotkin, Citadel CEO Ken Griffin and Reddit CEO Steve Huffman. Here are the testimonies here of the players involved and a link here to biographies of some of them. “A few things I am not. I am not a cat. I am not an institutional investor, nor am I a hedge fund. I do not have clients and I do not provide personalized investment advice for fees or commissions. I am just an individual whose investment in GameStop and posts on social media were based upon my own research and analysis.” ROBINHOOD CEO VLAD  TENEV: “We always felt comfortable with our liquidity... The additional capital we raised wasn’t to meet capital requirements or deposit requirements... “ “I recognize customers were very upset (from the restrictions on trading)... it would have been significantly worse if we had prevented customers from selling. “Not at all, zero pressure (from anyone on the panel to decide to restrict trading), it was a collateral depository decision.”