The IFCode used by 'Instant' for lets say color is:

[ color = "" ] text [ / color ]   (without spaces)

on some other forums they use

[color:red] text [/color]

What is the difference?

I had the same issue and ended up adding new IFCode so that those who post using syntax for other forums works with mine too.. i.e.

[color=Black][/color] <-- notice no quotes... was a code I used on my old ColdFusion site so when I ran the migration I noticed those popping up all over posts in the migrated topics... simply added it as an IFCode and it fixed the issue.

I add them and uncheck the "Display in Popup Dialog" option so you don't end up with multiple tags that do the same thing (at least in the popup IFCode window). 

I even added a new YouTube tag:

Friendly Name:

YouTube (Video Code is the value after v= in the url at YouTube.com)

Tag Example:

[youtube]Video Code[/youtube]

Actual Code to Insert:

[youtube][/youtube]

Search Pattern:

\[youtube](.+?)\[\/youtube\]

Replace Pattern:

<object width="425" height="350"><param name="movie" value="http://www.youtube.com/v/$1"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/$1" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"></embed></object>

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http://www.the-pork.net ... highly customized version of InstantForum. 

thanks for your help much appreciated