DO NOT PLAY THE VIDEO. (That's just a screengrab of it, not the actual functioning embedded video.)
The video contains a Windows rootkit virus that keylogs your passwords & posts spam using your LJ account, not to mention some other stuff that may be more sinister, all unbeknownst to you. [SOURCE: [Warning] Serious rootkit virus spreading in LJ comments by luma_chan ] ETA: 25 July 2012: In this comment by brooke, we've been discussing the LACK of recent anti-virus articles about trojans that exploit the YouTube Flash video codec. Neither of us can find anything about computer malware being spread via playing a video.
Known accounts [now up to 56] that generate these spammy malware comments:
Let's get LJ admins alerted to this exploit (the more reports, the better!) by following these instructions: 1. Hover your cursor over the little userhead next to the username.
2. In the box that pops up, click the "Ban user" boxes that apply. (Community owners & moderators see the "in my communities" ticky box.)
3. Click the "Report a Bot" link to notify LJ admin of the spam account.