In the first step download web video caster on your smartphone (For Android & iOS)
Assuming that you have installed Web Video Caster on your device, launch the app.
Tap the three-lined sandwich icon above to toggle the sidebar and select IPTV from the list of options.
Tap the + icon above, tap the field under IPTV address, and paste the M3U URL sent to you in first wellcome email by NFLHDTV.
Put a name for the IPTV list below (in this case nflhdtv) and click SAVE to add the IPTV list.
Click on the Cast icon
Select Roku to let the app scan your Roku device on the home network and tap DONE. Make sure your smartphone and Roku is connected to the same Wi-Fi network.
Head over to the IPTV section of the app to open the IPTV list you just added. Give it some seconds to load the playlist.
Once the IPTV list loads successfully, select a channel from the list or use the Search function above to search for a channel.
Select your Roku device on the next page, then click the Play button.