The distribution is what they really need to include. The average view time doesn't mean much when the distribution is super skewed, which it's likely to be for these ads.

If 0.1% watch all 30 seconds, 0.9% watch to 28 seconds and quit at the credits, and the rest all watch 0.2 seconds as they scroll through, that tells you something that "Average watch time = 0.5 seconds" doesn't tell you. Especially if last week, no one watched the whole thing, but a bunch of people watched for 2 seconds and then quit, and your average was 0.9 seconds.