I tried that link in Safari 4.0.5 and didn't get that message. FWIW, Real Player launched automatically and I could have used it to download the video if I had wanted to.

Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365