Hi,
We have added your request to support REGEXP in Object Browser filter here: http://code.google.com/p/sqlyog/issues/detail?id=1895
Further, with current OB Filter, as you type in edit box, first matching table name(word%) will be filled in filter text box. You can type table name unless you get the table you want and press enter, this will show only desired table in Object Browser.
Regards,
Shubhansh