Some YouTube videos are now featuring an ad that pops up midstream, in a display format in the lower part of the player, Lost Remote observes
. The blog illustrates the ad format with reference to the CBS-uploaded clip of a "Frosty the Snowman" promotion. After the ad folds down, a small ad button occupies the lower right of the screen. The ads don't necessarily travel with embeds of the segments on others sites, however.