Marketers simply cannot afford to ignore video advertising. eMarketer predicts that video ad spending in the US alone will reach $15.42 billion this year, and will grow to $22.18 billion by 2021.

New research from artificial intelligence-powered video creation service Wibbitz provides some insight into which social media platforms video advertisers should be paying attention to—and it's pretty much what you would expect.

The firm's December survey of US internet users found that nearly three-quarters (73.9%) used Google's video juggernaut YouTube—or Vimeo—to watch video content. It's probably safe to assume that Vimeo accounted for a small portion of viewers, given that the platform caters almost exclusively to professional content creators (or those aspiring to become professionals) with videos boasting high-end production values.

Facebook was close behind, used by about six in 10 respondents, while roughly one-quarter tuned in to video on Instagram.

Wibbitz's data makes sense when considered along with recent research from Wyzowl, which found marketers worldwide considered YouTube and Facebook to be the two most effective video platforms for marketing, in that order.

The Wibbitz study also indicated that only about 10% of respondents engaged with most of the videos they viewed on social media. Meanwhile, more than half said they would only engage with videos they deemed relevant, underscoring how important market segmentation and targeting tools are for advertisers looking to buy inventory on social video platforms.

When it came to the types of content US internet users liked to watch, entertainment topped the list, named by 56.5% of respondents, Wibbitz found. That was followed by how-to videos (51.0%), news stories (48.4%) and educational and informational videos (47.6%).