You will find answers to many questions here:
Specifically, for answers about the VDH license, do a string search for "philosophy"
within the text of that web page. That will reposition the page on a reference that
contains a link. Click the link & read up on the VDH license. I will say that you can
buy VDH licenses for more than one browser. You don't need to wait for the refund to get
the second license. You can choose to wait or you can buy the second license now, it's
up to you.
I don't think you can get an unbiased answer about which platform is most stable.
Everybody has their favorite browser. I will say that the developer develops VDH on
Linux & he seems to have a preference for Firefox. Of the 3 browsers on which VDH is
available as an extension, beta versions of VDH are available only for Firefox. The
current latest beta of VDH for Firefox is 7.6.3a6, and it is the same as what is supposed
to be the latest general availability public release, which will be 7.6.3. I say will be
because Mozilla has been sitting on the release of this version for over a month &
there's no predicting when they will condescend to approve it. In the meantime, you can
get the beta off the VDH web site. You can learn how by doing another string search on
that same web page, using the search key "various pieces" this time.
I use Firefox & I have done livestream recordings lasting as long as 6 hours. That's
just to dispel any doubts you might have about whether the length of the item is a factor
in VDH's success.