In a case like this, some browsers will not break the string at all by default, some will break after a hyphen “-”, some may also break after a slash “/”. If you really need to have a long filename in a table cell, you need to decide what you want—what would be the least of evils.
After the decision, use nobr
markup to prevent line breaks and wbr
markup to allow them, or their character-level or CSS counterparts (which work less widely). There are many nasty details involved; see my page on preventing and allowing line breaks.
Breaking after “-” is problematic because the reader won’t know whether the hyphen has been introduced in word hyphenation or is part of the filename itself. Then again, does this matter? What is the reader supposed to do with the long filename? In this case, the “filename” looks really like a URL without the “http://” part, and in such cases, it is better to use a descriptive link text (which may wrap freely) and put the URL where it belongs, an href
attribute.