After the new GDPR Changes have Valve Made it's now possible to watch Wingman Demos, Here's how you made it:

1. Open your browser (Google Chrome, Mozilla Firefox, Microsoft Edge, etc..)
   
2. Go to your profile and then go to games.
   
3. You want to find Counter-Strike: Global Offensive > next to it you should see a button that says "personal game data"
   
4. Navigate to the tab saying "Wingman Matches"
   
5. Once on the matches click "Download GOTV Replay" to the left of the demo stats - a new window should open and then you must copy the link and paste it into a normal internet browser and the file should be downloaded.
   
6. Now you want to extract the .bz2 file, I used 7zip for this
   
7. Once here drop the extracted .dem file into here (steamapps\common\Counter-Strike Global Offensive\csgo)
   
8. Go InGame type type demoui in console or hit shift+f2 then press "Load" Button and select the .dem file you extracted and placed on csgo folder

05/01/2019 - Updated. Thanks @.#𝚌𝚊𝚞𝚜𝚝𝚒𝚌
15/12/2020 - Thank you for those who've awarded this guide!