Replay Buttons

When I want to replay something, I mean play the video again. I don't mean stream the entire thing again just in case I missed an entire pixel. Just show me what I already watched, AND DOWNLOADED, again! Not all of us have T3 lines in our basement. I had a 56K modem 7 years ago. Do I look like I'm advancing with the technological curve? Youtube figured it all out at CONCEPTION. Why are websites still doing this?!