Red Button now on iPlayer

[RS]

I was very grateful to Vangelis for telling me how to find the PIDs for Red 
Button coverage of equestrian events in the Olympics.  The BBC now seems to 
have made it slightly easier.  The coverage of the Badminton cross-country 
on 5 May is now in the iPlayer as two 3h programmes.  The PIDs are b08r3nv4 
and b08r3pmr.

There are some oddities.  The first thing I noticed was a large discrepancy 
between the modesize and the estimated file size for the download.  The 
explanation appears to be that the duration is shown as 7200 and the runtime 
as 120 whereas the programmes are in the region of 3h.

There are no HLShd modes, but this appears to be normal for Red Button 
coverage.  The highest resolution available is HVFxsd.  I have hvfxsd2 in 
my --tvmode as a fallback so that is what was used for the first programme. 
The download speed was only about 10Mbit/s when I was expecting it to be 
about 40Mbit/s.  For the second programme I looked at -i -v.   There are 9 
HVFxsd submodes, and there appears to be a new CDN.

There are lines which begin
INFO: Found mode
For hlsvhigh1 the string ends
(CDN: akamai_hls_open_https/100)
For hvfxsd2 it ends
(CDN: mf_limelight_uk_hls_https/10)

I wondered whether the 100 for hlsvhigh1 meant it was limited to 100Mbit/s. 
I am used to getting up to 80Mbit/s for hlshd.  Could the 10 for hvfxsd2 
mean it was limited to 10Mbit/s?

The highest number I could find for hvfxsd was 30.
For hvfxsd1 the string ends
(CDN: mf_bidi_uk_hls_http/30)
I downloaded the second programme with that mode at about 18Mbit/s.

Does this mean we need to select modes very carefully to get the best speed? 
For hvfxsd5 the string ends
(CDN: mf_akamai_uk_hls/1)

All the above was done with get_iplayer 3.00 in Windows 10.

Can anyone shed any more light on this?