" You shall not download any Content unless you see a “download” or similar link displayed by YouTube on the Service for that Content. "
https://www.youtube.com/static?template=terms
This is partly why you find so little help on that. Also, so many Youtube downloaders are trojaned, infected or just malware.
So there it is. Many folk want to download so for Youtube we just look for the download button. Asking for help is like asking for help to jack a car. Please don't.
As to Dailymotion they may have a similar service agreement so again why there is so little help for this.
I would like to find out about video+audio capture/download from youtube and dailymotion using a Mac (OS X Yosemite 10.10.4). I tried using Airplay on Apple TV and connecting an Pioneer DVD recorder but that doesn't work. So I wondered if there was software available to record directly to Mac (and then possibly convert with Handbrake). I found a CNET review of Kigo Video Downloader for Mac which may work but not sure. Also didn't know if there might be some type of USB connector I could connect my Mac directly to the DVD recorder and save that way. Any help would be greatly appreciated!

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