The W3C recommended SMIL in June 1998, but that doesn't mean it will be universally supported across the Web. Quicktime 4.0 supports SMIL (1999)
All emerging standards have opponents, and SMIL is no exception.
No Web browser currently supports SMIL, and Microsoft and Netscape have no plans to support the standard anytime soon. In fact, even though Microsoft helped develop the SMIL 1.0 specification, Microsoft now says SMIL is not mature enough to support, claiming it overlaps with several other technologies, such as Dynamic HTML and the Document Object Model. (Microsoft's streaming media player NetShow does not support SMIL either).
Probably the real reason Microsoft stopped SMILing was the fact that Microsoft, along with Macromedia and Compaq, submitted (March 1998) its own synchronized multimedia proposal to the W3C, called HTML+TIME (Timed Interactive Multimedia Extensions for HTML). This proposal claims to address SMIL's limitations:
However, SMIL does have an active following on the Web. RealNetworks' RealPlayer, the most common streaming media player on the Web with 85 percent of the market, supports SMIL in its G2 player.
Major media companies such as CNN Interactive, Fox News, the History Channel, and dozens of others have already begun to offer SMIL-based content via its RealPlayer G2.
Many other SMIL-compliant players, authoring tools, and servers are also becoming available.