I generally find coverage on TV for anything horse related (bar racing obviously) to be pretty naff. It's normally never on when I can watch it and rarely if ever advertised.
I believe that The Country Channel are filming this weekend but it may take a little time to get it up online as they do not have the facilities to go live to air.
With the BBC cutting right back on outside broadcasts, it is increasingly difficult to get funding to film events and many organisers just aren't clued up enough on the power of streaming video etc etc to appeal to a wider audience than might be able to attend the event in person.
Keep an eye on the Country Channel - it is all free to view but Blenheim may take some days or weeks before it appears on their site.
Ref. quality of non racing stuff - I work for the company who film most of the racing on behalf of the media channels (BBC, C4, Racing UK and ATR) - the online horsey channels are starting to get to grips with the need for quality to attract sponsorship to fund "professional quality" filming - Point to Point too, but it is going to take some time - as usual it all comes down to money. It is not difficult to do technically, but racing is well funded and other equestrian sports are less so.....we hope to be able to get involved with other horsey stuff next year as current material is, as you say, "pretty naff"!