line = 'User Number 1 will probably like movie ID: RecommendedItem[item:557, value:7.32173]the most!'
content = '557::Voyage to the Bottom of the Sea (1961)::Adventure|Sci-Fi'
import re
m = re.search(r'(?<=RecommendedItem\[item:)(\d+)',line)
n = re.search(r'(?<=^'+m.group(0)+r'\:\:)(\w+)',content)
print n.group()
bGluZSA9ICdVc2VyIE51bWJlciAxIHdpbGwgcHJvYmFibHkgbGlrZSBtb3ZpZSBJRDogUmVjb21tZW5kZWRJdGVtW2l0ZW06NTU3LCB2YWx1ZTo3LjMyMTczXXRoZSBtb3N0IScKY29udGVudCA9ICc1NTc6OlZveWFnZSB0byB0aGUgQm90dG9tIG9mIHRoZSBTZWEgKDE5NjEpOjpBZHZlbnR1cmV8U2NpLUZpJwppbXBvcnQgcmUKbSA9IHJlLnNlYXJjaChyJyg/PD1SZWNvbW1lbmRlZEl0ZW1cW2l0ZW06KShcZCspJyxsaW5lKQpuID0gcmUuc2VhcmNoKHInKD88PV4nK20uZ3JvdXAoMCkrcidcOlw6KShcdyspJyxjb250ZW50KQpwcmludCBuLmdyb3VwKCk=