As introduction, TubeDownload.us is a online tool support download video from video sites. However, We are not hosted and have not license about those video. All video display on us site it embed from site publish (ex: youtube, vimeo...) with embed tool of each site.
If you want download and using it for your purpose you should read infomation about license of each video on publish site or contact to video owner.
If you are the video owner and you don't want your video display on us site. you can set share permission on video site you was posted (ex: youtube set private). When your video remove on publish site it also remove on us site.