Two seconds According to Google, there’s no average length for this metric in bumper ads. Four seconds One second Download Google Ads Video Certification Exam Answers (PDF)
Non-skippable in-stream ads are available on YouTube and advertiser websites. Non-skippable in-stream ads are available in auction or as a reservation buy. Non-skippable in-stream ads can be bought on target CPM or CPD. Non-skippable in-stream ads are six-second ads that show before a video. Download Google Ads Video Certification Exam Answers (PDF)