Analysis of the campaigns' Twitter accounts showed the gap between the campaigns increased from approximately 8,000 followers in August 2013 to 13,804 followers in February 2014, in favour of Yes Scotland. The project published a further report in June 2014 saying that greater online activity for Yes Scotland had continued. Professor Michael Keating said in April 2014 that the pro-independence movement was visibly stronger and fighting a "ground war", while unionist supporters were fighting an "'air war' of facts and figures". The launch of online celebrity videos from both viewpoints was reported by the media in mid-July 2014. The "Let's Stay Together" campaign group produced a YouTube video called "'Scotland, you're my best friend'", featuring John Barrowman, Ross Kemp and Eddie Izzard. A pro-independence video was produced by Yes Scotland and appeared on the campaign's YouTube channel. Titled "✘ on September 18th #voteYes", the video features 32 people, including David Hayman, Martin Compston and Stuart Braithwaite. The pro-independence organisation National Collective was identified by the "Independent" newspaper as the initiators of an online hashtag campaign that began in mid-August 2014. Writing for the "Independent", Antonia Molloy said that the previous "#IndyReasons" hashtag campaign served as the inspiration for the "#YesBecause" campaign that was observed on the Twitter, Facebook and Vine social media platforms. From 21 August, users were invited to explain their reasons for voting "Yes" and #YesBecause was trending on Twitter after an hour from the launch. The Canadian Broadcasting Corporation (CBC) reported on 22 August that a "#NoBecause" campaign emerged in opposition to the Collective. Debates over the issue of independence took place on television, in communities, and within universities and societies since the announcement of the referendum. The STV current affairs programme "Scotland Tonight" televised a series of debates: Nicola Sturgeon v Michael Moore, Sturgeon v Anas Sarwar, Sturgeon v Alistair Carmichael and Sturgeon v Johann Lamont. On 21 January 2014, BBC Two Scotland broadcast the first in a series of round-table debates, which was filmed in Greenock and chaired by James Cook. The Yes campaign repeatedly called for a televised debate between UK Prime Minister David Cameron and First Minister of Scotland Alex Salmond. These calls for a one-on-one debate were dismissed by Cameron on the basis that the referendum is "for Scots to decide" and the debate should be "between people in Scotland who want to stay, and people in Scotland who want to go".