Simply remove your OR and leave a space.
From the Fiddler Book
The Show only if URL contains box allows you to hide requests whose URL does not contain a required string. You can demand case-sensitivity using the EXACT prefix:
…or you can use a regular expression:
REGEX:(?insx).*\.(gif|png|jpg)$ #only show image requests
You may enter multiple strings delimited by a space:
Term1 EXACT:Term2 REGEX:.*term3$
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