This initial scene is taken from the original series, it has been copied into the video to add to the authenticity of the text. The effect they were going for was to look like they were starring in a happy days episode.
This scene reveals the band within the scene, the filming has been done on a old school camera and the band has been placed in using specialist software, to look like they are in the scene (This has not been done on the above photo, this is just filming that has been cut in)
This shot has been very cleverly done, the original "owner" of the series has been placed in the scene to again add to the authenticity.
The videos are very similar, but the whole concept of the weezer video was to emulate that of the original Happy days series. By using specialist editing to place the weezer members onto several scenes from happy days. Other similarities include the clothing worn, weezer have been sure to dress in period correct clothing, also they have used an affect over the whole of the videos filming such as the below image
The camera used would have been correct for the time period, then added to the video.