A new report on engagement with online video reveals that search engine optimisation is a crucial strategy for publishers.

The Online Video and the Media Industry report from Brightcove and Tubemogul has found that outside of direct traffic, the highest volume of referral trafic for online video content comes from Search, followed by social networks.

As Search Engine Watch’s “Zemanta” notes, the report is far from comprehensive – two of its three data sources come from internal customers, whilst the third uses Tubemoguls distribution and analytics platform. Even though ”over 175,000 users rely” on this platform, it should be noted that it only represents a tiny fraction of the online video market. Still, it provides an “interesting view” on the significance of search in online video.

Overall, direct traffic was the main source of discovery for the video streams contained in the sample (51.75%) – for the most part, it seems a publishers website still forms a critical hub for online video. However for the remaining 48.25% of external traffic, it seems search engines are currently the most influential source, with Bing, Yahoo and Google driving 46.79% of all external views.

Unsurprisingly given its massive user base, Google took the lions share of this traffic (38.92%), followed by Yahoo (5.58%) and Bing (2.29%). Conversely, Facebook – the next biggest source of traffic – only accounted for 0.40% of external traffic.

Whether or not the search traffic is driven by organic performance (SEO success) or by paid advertising (PPC bidding such as AdWords) is unclear from the report. Still, it indicates that search engine marketing is a powerful factor in online video.