Just posted on the Google Blog is word of interface tweak on the Google Video site that enables you to search "all video" (still images/transcripts from telelvision programs AND playable video) or limit your query to only playable video. This is something I wished for in a recent post about Google Video.
You can also limit your query using some search syntax. I blogged about it last week. Use source:upload [foo] in your query for viewable video or source:tv [foo] to find images/transcripts from television.
Postscript: You can also use the syntax playable:true [foo] to limit a search to viewable video.