Viral marketing is a modern form of marketing communication that takes into account the specifics of consumer behavior within the framework of the Web 3.0 public information paradigm. Effective implementation of a campaign requires study of the communication environment. The article analyzes the existing social networks and their users. Active users act as relays for the message. The concentration of active users determines the communication activity of the social network. The sample of the study consisted of 101 social networks, which were classified according to the following criteria: content subject; Yandex search statistics result; Google search statistics result; text, photo and video content availability; on-line games availability; file sharing within the network. As a result of the analysis, a set of social networks in 30 different thematic groups on the basis of which viral video campaigns can be conducted has been identified. Video streaming sites are also part of the communication space. The article provides a brief review and analysis of the following video hosting services: YouTube, Rutube, Видео@Mail.Ru, Яндекс.Видео, Сибнет.Видео, Flickr, Myvi, BigMir, Tvigle.ru, Vimeo, MetaCafe, Dailymotion, Vevo, HowCast, VK, OK, Smotri.com. We have proved the expediency of basic hosting on a YouTube channel with subsequent retransmission to other thematic hosting services. We have analyzed the trends of YouTube as a market of viral videos. The initial sample of the analysis was 3500 channels with Russian-language content and more than 1000 subscribers. The top 10 channels by number of subscribers and by number of views were selected from 15 thematic groups, which allowed to identify the most popular topics of video; the relationship between the total views and the total number of subscribers, the relationship between the daily changes in these parameters. The tendencies characteristic for the communication space of viral video marketing have been defined.