You just need to plug a network ethernet cable into the box and use a DLNA/UPnP-compatible media player on your devices. There are a number of them, like VLC. The player should be able to find the HDHomeRun and off you go. The HDHomerun Extend does transcoding so it can get hot and it does have a fan that can be annoying.
I've been using the connect version for years and that is even simple to use with VLC. Since there is no compression, just passes along whatever the TV station is broadcasting, it is a network hog, however. The connect would not work well over a wireless network, where the extend should be OK..
If you want to record, EyeTV ($70) or MythTV (free) are good choices. You can then stream the recordings.