More often than not, these ad spots last for less than 20 seconds. In-stream video spots are broadcast on specialized platforms like YouTube, but also from specialized publishers (IMDb, on-demand TV). Comparable audio spots might play on apps like Spotify or Pandora, and are generally inserted in real time depending on targeting criteria chosen by the advertiser.
Depending on the platform, users might be able to “skip” the ad and directly access the desired content.