Globe and Mail: Google is launching an advertising campaign aimed at attracting more advertisers to its online video service, YouTube. The ads, which will appear online and on billboards and transit ads in Toronto, are part of a larger effort to increase YouTube’s audience and the star power of its highest profile video creators. It also follows on changes the tech giant has made to how it sells ads on YouTube, which have been a success in the United States and are now rolling out in Canada.