Though in-stream ads are popular with advertisers, a new study shows that viewers do not share that enthusiasm.

A study by Forrester Research discovered that 80 percent of web video viewers said in-stream ads - those placed before and after video clips - were "annoying," and 75 percent said they ignore them, AdWeek reports. The study also found that viewers were much more likely to accept ads placed alongside clips, or text-based ads.

In-stream ads are popular with advertisers because they make messages easier to convey to viewers. But those viewers are used to viewing video clips on sites such as YouTube without these placements, which they now view as intrusive.

"When you see what's going on with YouTube and short form content, using the old mode of inserting ads into content when you're looking at a three-minute video is not going to work as well," said Forrester Research analyst Brian Haven.