FMCG companies are the biggest online video advertisers in the UK

"FMCG advertisers overtook entertainment as the biggest spenders in online video with impressions surging 66 per cent quarter on quarter, according to figures from addressable audience platform Videology.
The report, which marks the third in a series of Videology-led research that will be published exclusively on The Drum, is based on 553,197,168 video impressions in the UK during the first quarter of 2013 – up from the 465m impressions tracked in the previous quarter."

Source:  The Drum, 10th June 2013

Note - Ad tracking based on tracked impressions may be a bit arbitrary - see also Nielsen's Ad Relevance