Im also on the Nexus 5 having no MP4.
I tried using the UTMedia with copy / paste (or reboot) method without success, instead I get another error!
Im directed to download this:
file:///opt/click.ubuntu.com/utmedia.nfsprodriver/0.14/www/index.html

So I tried video conversion from mp4 to webm.
VP89 VIdeo File in Webm container
Now Im getting sound with a black display.
So which codecs are safe?
Vlc Options:

* H.2Options64 video format  in MP4 file container
H.264 video format in TS file container
Dirac video format in TS file container
MPEG video format in TS file container
Theora video format in OGG file container
WMV video format in ASF file container
DIV3 video format in ASF file container
MPEG 1080p/720p video format for TV/device in MP4 file container
DivX video format in AVI file container
SD video format for iPod in MP4 file container
HD video format for iPod HD/iPhone/PSP in MP4 file container
SD low and high video format for Android in MP4 file container
VP89 VIdeo File in Webm container

Just took a road trip to Pittsburgh, have good reception everywhere and all along the Interstate coming here!

I'm trying to get a friend setup with UT!!
They want CDMA only!
I'm running Nexus 5 and waiting for the PinePhone

Thanks for all the info!
Ok so I just updated the radio firmware to the latest as mirroronthewall suggested.
No difference so far.

One more thing I may have made a mistake regarding the APN.
The only APN is Internet / MMS for wap.tracfone & mmms.tracfone.com.
I made the mistake of trying to create my own LTE APN (which is disabled). But I can't delete it, rather the phone reboots with enabling both APNs??? How do I delete?

This is not just a coverage issue, but a StraightTalk & TMobil decision of some sort.
There is 3G / 4G coverage here but my phone is denied on the tower over our house.
I have a used Kindle Paper White here I bought used as a gift (and preloading with Gutenberg) and it has full bars on 3G here.

Hello!
I flashed a Nexus 5 without much difficulty thanks to the UBPorts application.
I'm getting 4g connection, and even 3g I think, when I am traveling around our area.
But when I am home I have zero connection even though we are 'covered' on the TMobil map.
Working with support I squeezed out the following fact:
"T-Mobil(or MVNO) will not support this phone on this tower in your area less than 4g"

Please let me know what I can do.
1.) Try the OnePlusOne instead?
2.) Flash the phone back to Android to activate first, then flash back to UT?
3.) Adjust APN settings further?

When I activated the phone StraighTalk told me the phone is not allowed only a SIM connection...
While traveling I adjusted the cell connection to be only 3G/2G and the connection icon says 'E' but I don't know what that means?
Will the PinePhone work with UT?