The anti-semites like to go overboard with "finding the Jew", sort of like Alex Jones seeing NWO agents under every rock. But there is a kernel of truth to the Communism arguments.
The Reform Judaism movement had as its goal assimilation with the local culture while retaining the important parts of Jewish religion, whereas before then Jews largely lived very seperate from society. Their pre-19th century lifestyle reminds me of the Amish in many ways, though not as extreme. This assimiliation aproach of the Reform movement was successful in Lithuania(?) until Czarist Russia conquered the territory. The Czar was extremely cruel to the Jews, as bad or worse than any other dictator who attacked Jews in prior history. This disillussioned many Reform Jews. Part of the reason for the assimilation was to become more welcomed by host populations, and instead they got worse cruelty than before. This gave Reform Jews in Russia an incentive to rebel against not only the government but also the local culture. And replace it with what? The experience also had a second affect: dissillusionment with traditional Jewish thought in general, leaving an intellectual vacuum that was ripe to be filled with all kinds of crazy ideologies, including Communism. These two factors coming together led to Jews having a disproportionate impact on waging revolution against the Czar and pushing communism as its replacement. This is basic non-controversial history. You can hear similar sentiments from Jewish talkshow host Michael Medved or from rabbi lectures on history/ (I recommend the Rabbi Ken Spiro series on Jewish history from an Orthodox perspective. He covers the things i describe above very well.)
Like most revolutions, there were a variety of factors in play with each faction having its own motivation for their own self interest. Russia had the largest Jewish population in the world. They went from being prosperous, upstanding members of society to destitute slaves under the Czar. Go read up on how the Czar treated them. Then is it any surprise that they would work to overthrow the Czar? And is it any surprise that the Jews that did get into post-Czar seats of power in Russia abused the power? The point lost on many anti-semites (especially the socialist varieties that praise big government): those Jews who did gain political power wielded it pretty much the way everyone wields political power: evilly. Power corrupts everyone.