Alexey Navalny has had a tough week.

On Dec. 26, the Russian opposition activist was barred from running against president Vladimir Putin in the 2018 presidential election. He responded by telling people to boycott the election and called for mass protests at the end of that month. Today, a video (in Russian with English subtitles) in which he makes that call, mysteriously disappeared from YouTube for more than an hour.

It’s not clear why the video was blocked and then returned to the website (Google, YouTube’s owner did not immediately respond to a request for comment, but we’ll update if it does). Despite the video’s quick return, Navalny complained and alleged that the temporary removal was down to a Kremlin plot. He said that by taking it down, even for a short time, was “in a certain sense successful” because, he says, it no longer appears in YouTube’s trending videos, meaning fewer people will see it.

An anti-corruption activist who led mass demonstrations after the 2012 elections, Navalny was barred from running against Putin next year because of a previous criminal conviction. In 2013, a Russian court convicted him of embezzling timber worth 16 million roubles ($278,000), but in 2016 the European Court of Human Rights ruled he hadn’t been given a fair trial. A Russian court retried the same case in Feb. 2017 and gave him exactly the same five-year suspended sentence as in the original trial.

Navalny has gained a large following despite never being allowed to appear on state-run television, and Putin and his circle doing their best to never say his name. He is appealing the decision to bar him from running in the election.