I took my tablet into the end of my garden which is about 30ft long and I was supprised to be getting WiFi is this normal
Providing there is little between you and the router then 30ft is not out of reach. My router goes through one wall and easily gets 50-60ft.
and if I have downloads from YouTube will they play without WiFi.
Not sure I understand this, without the internet you can't download from the net or watch files on YouTube. However, if you have already downloaded the files then providing you have the correct software to play the files then yes you can play them without "WiFi" Blinky