(For those curious: from the US, using Chrome, no ad or privacy block - Facebook is outputting 21 lines of HTML and then nothing. Looks like PHP is just dying for some reason)
The tl;dw is that the Democrats changed their debate qualification threshold from polling at 1+% < 6 weeks before the debate to polling at 1+% > 6 weeks before the debate. This means Lessig went from probably-in-the-next-debate to definitely-not. He figured if the Democrats are actively changing their rules to disqualify him, his effort is probably best spent on things other than running for a primary that doesn't want to include him.
Or watch the version on YouTube: https://www.youtube.com/watch?v=u4IsqmMqCEo