For months, YouTube's co-founders, Chad Hurley and Steve Chen, have walked a fine line between encouraging their audience to upload video clips and soothing the nerves of anxious rights holders who could have crippled their fledgling start-up with copyright lawsuits.

Even after the group's $1.65bn acquisition yesterday by Google, some observers remained sceptical that even Google and YouTube combined would be able to overcome the technical and legal challenges posed by copyright.