Flickr Pro members can now upload videos of a maximum length of 90 seconds to their Flickr photostream now that Flickr has launched their Flickr video sharing service.

As for where the videos will be shown, Flickr says:

Video will display alongside photos in search results, within new uploads from friends, in Explore, on the Map, in RSS feeds, and anywhere else that you are used to finding photos.

There will be some parts of Flickr where you can choose that you’d like to see either photos or video, or both, such as Advanced Search. There’s also improved group pool submission rules so group admins can specify whether they’d like their group pool to include photos, or video, or both.

Although Flickr videos are not yet indexed by Yahoo video, it may be what they are planning in the near future, the same way that Yahoo Image Search currently provides live images as they are uploaded by users from Flickr photostreams.
Regarding the 90 second limit, Flickr mentions:

Video on Flickr grew out of the idea of long photos and as such, we’ve implemented what might seem like an arbitrary limit of playing back the first 90 seconds of a video. We’re not trying to limit your artistic freedom; we’re trying something new.