YouTube by far dominates, delivering 10 times as many streams as its nearest rivals. Competitor services such as Hulu, however, are seeing significant growth. YouTube streamed 6.4bn clips, reaching 106m unique viewers. Hulu, which signed musiccontent deals with EMI and Warner Music late last year, streamed 635m videos to 13.6m unique viewers.
In total 137.4m people in the US watched online video last month, an increase of 10.3% from December 2008. Over 10.7bn videos were streamed in the period, up 11.8% from a year earlier.
Figures for premium music video channel Vevo were not included in the Nielsen figures which listed the 10 leading online video sites.
Figures published this week show that five of the 10 most viewed videos of all time on YouTube were music-specific. Alongside Susan Boyle's audition on Britain's Got Talent, the other four were promo videos.
The video for 7 Things by Miley Cyrus was the most watched music video (108.5m views) followed by Pitbull's I Know You Want Me (92.4m), Susan Boyle (85.1m), Timbland's Apologize (81.2m) and Say OK by Vanessa Hudgens (78.6m).