the sponsor label appears above video thumbnails (i.e. before you click on the video) when using the sponsorblock extension.

you may not want to watch a video after seeing the label, as it generally means that the video will be biased towards a product or service, (e.g. a review) or that most of the video is sponsored content (e.g. a skit about said item)

the top screenshot was taken from their wiki, the bottom one (the full-video label that appears above videos) was taken from a sponsored video

this section has been spoilered as saying the name of the extension makes me feel like I am advertising, (which makes me feel uncomfortable) in addition to significantly inflating the size of the description

the title and first line of the description is a reference to a PBS bumper