LONDON: Increased viewing of online video clips has created an emerging market for "shortcast" contextualised video advertising, according to Yahoo.

A new study by the internet group estimates that 70% of UK internet users watch short form clips - defined as under five minutes - at least once a week.

Respondents showed higher levels of advertising acceptance when clips were high quality and appeared in trusted editorial environments rather than free uploading websites. 

Some 70% of viewers said the image quality of clips was important to them, with 22 seconds reckoned as the optimal length for a pre-roll online video advertisement.

Genres such as sport, news, television shows and film trailers dominated clip viewing, and the study argues that video ads are more likely to be accepted if they match the genre of adjacent content.

Yahoo believes the rising global sales of tablets such as Apple's iPad2 will also grow the popularity of short form clips and expand the possibilities for shortcast advertising.

The Yahoo study combined a survey of 2,000 UK consumers' online viewing with quantitative research, and estimates that 38% of respondents who reported watching short clips at least once a week did so on a tablet.

The figure is on a par with mobile phones but currently lags behind laptops (68%) and desktops (67%).

Patrick Hourihan, head of UK trade research, Yahoo UK & Ireland, predicted that tablets could have a huge impact on the online video sector, citing a 2010 Nielsen prediction that 11% of global internet users would own a tablet within 12 months.

Others contend that the growth of web-enabled televisions could prove a bigger catalyst for the online video market.

The UK online video advertising market remains modest, if fast-growing, with an estimated £54m ($87m; €61m) a year spent on the segment.

Advertisers have concerns about the difficulties of demonstrating the return on investment from an online video campaign or showing that it can cost-effectively add reach to an existing TV campaign. 

Data sourced from Warc