why did this tape of Trump saying those things surface now?
Its 11 years old.
I am amazed that the news pundits are worrying about the what (the tape)
and not the why (the timing)
There's no mystery there. Someone who doesn't like Trump sent the tape to the NY Times. The Times sat on it for five days while their lawyers considered their legal exposure (Trump knew he was being recorded, but he is famously litigious--he's been a part of 3000 lawsuits, roughly half as plaintiff and half as defendant). The source got tired of the delay by the Times so they sent it to the Washington Post. WaPo spent five hours vetting the tape and released it.