Unintentional nested list of POSIX paths in Applescript
Try:

set sourceFolderPath to POSIX path of (choose folder with prompt "Please select directory.")
if sourceFolderPath ends with "/" then set sourceFolderPath to text 1 thru -2 of sourceFolderPath
set findResultsList to paragraphs of (do shell script "find " &amp; quoted form of sourceFolderPath &amp; " -type f -flags nohidden -iname '*.VOB';")
set AppleScript's text item delimiters to {"|"}
set findResultsText to findResultsList as text
set AppleScript's text item delimiters to {""}
return findResultsText