1. Open up VLC Media Player
2. Simply Drag & Drop the downloaded m3u file into your VLC or open it via Media > Open File > "Choose your .m3u file"
You now should be able to watch IPTV
In order to switch Channels go to "View" in the Menu strip and navigate to "Playlist"(CTRL + L or command + L on MAC)
You will now see a list of Channels available to choose from you can use the search function to find a Channel.