PVR run problem on latest W10 insider build
I am on the W10 insider programme and was recently updated to version 17713_rs5 (preview for the autumn version)

The PVR start appeared to fail - the script ran but stopped with http://localhost:1935 the parameter is incorrect as a dialogue, and access not permitted in the command window

I tracked it down to a change in the way Windows handles the start <URL>  syntax.    I have edited my copy of get_iplayer_web_pvr.cmd so it looks like this:

ping -n 5 -w 1000 > NUL

rem - the start line does not work in the latest W10
rem   start http://localhost:1935
rem   call explicit browswer instead

"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" http://localhost:1935
Thanks for the heads-up, though that sounds a bit mad to me. Are you sure it isn't just objecting to the use of "localhost"? If not, can you post info what exactly is going to change with START? Embedding the path to a specific browser isn't a workable general solution.
Googling tells me that this is a bug in insider builds. People are reporting that things are OK with Edge as default browser, but not with any other default browser. If autumn release is nigh and it still isn't fixed, post again.
Not just localhost. I tried a few urls from a command widnow, including the start www.microsoft.com from Micosoft's own support forum from a few years back.

No idea what they are planning to do, but I have reported it as a bug in the feedback hub. There is already a general complaint about it there (https://aka.ms/AA20f9q if you have a login)
Still waiting for the autumn update, but running preview 17744.rs5 and the original start command behaviour of using the default browser appears to have been restored, at least in this version
Thanks for the update. One less thing to worry about.