[genezeta]

No, browsers did not have native support for video before the <video> tag.

Late 90s:

Netscape and IE, the main browsers at that time had generic plugin support through <object> and <embed>. What this did was load a plugin if it was indeed installed in your browser.

There were various video plugins available at various moments, e.g. Quicktime (.mov), LiveVideo (.avi), some Java and ActiveX... From the IE3.0 beta press release here [0] (1996) you can see mentioned some of the support for those things.

Again, you had to have the plugin which may not have been available for specific browsers or OSs. An additional problem is you needed to have an appropriate codec.

Early 00s:

Around ~2002 Flash started supporting video with FLV files. This still meant requiring the flash plugin but by that time it was fairly common. When YouTube started in 2005 it played through Flash.

HTML5:

HTML5 was released publicly ~2008 but didn't become a W3C recommendation until ~2014. Discussion on <video> started ~2006-7 but actual support still needed a few years more.

[0] https://news.microsoft.com/1996/05/29/microsoft-internet-exp... (search for "video")