There is no way to select an H.265 feed, for a number of reasons.
1) H.265 is not supported natively in most web browsers, and likely never will be due to licensing costs. Can I use... Support tables for HTML5, CSS3, etc
2) I could theoretically include an H.265 decoder compiled to JavaScript, however the higher computational cost of this versus H.264 decoding would not be good.
3) Blue Iris's web server can't encode H.265.