Cape Canaveral - A pair of Russian cosmonauts ventured outside the International Space Station on Friday to install two cameras that are part of a Canadian commercial project to stream high-definition video from space to subscribers over the Internet.Station commander Oleg Kotov and flight engineer Sergey Ryazanskiy left the station's Pirs airlock at 08:00 as the complex sailed 420km over Australia, mission commentator Rob Navias said during a Nasa Television broadcast of the spacewalk.It was third spacewalk this week by members of the station's six-man crew. Nasa astronauts Rich Mastracchio and Mike Hopkins made spacewalks on Saturday and Tuesday to replace a failed cooling pump.On Friday, Kotov and Ryazanskiy quickly completed the first item on their to-list by installing a high-resolution video camera on a swivelling platform outside the station's Zvezda command module.The video camera, along with a medium-resolution still imager to be installed later during the spacewalk, are owned by Vancouver-based UrtheCast Corp. The company in 2011 signed an agreement with the Russian space agency, Roscosmos, to install the cameras outside the station, a $100bn project of 15 nations.UrtheCast intends to provide free, real-time views of Earth to subscribers via the Internet. The 1m video camera also can be aimed at specific locations as the station flies overhead to image sporting events, natural disasters, large-scale public protests and other activities.UrtheCast intends to parlay its Internet viewership into sponsorships and advertising deals. It also plans to sell its space images directly to commercial companies, such as agriculture and mining firms, and to government agencies that buy satellite imagery."Video and still image data captured by the cameras will be downlinked to ground stations across the planet and displayed on the UrtheCast web platform, or distributed directly to exclusive partners and customers," the company said in a press release."UrtheCast's cameras will provide high-resolution video and imagery of Earth that will allow for monitoring of the environment, humanitarian relief, social events, agricultural land, etc.," the company said.Kotov and Ryazanskiy also plan to replace several science experiments outside the station during their seven-hour spacewalk.