I have a CSV file containing user (tweetid, tweets, userid).
396124436476092416,\"Think about the life you livin but don\'t think so hard it hurts Life is truly
Can't comment, but from looking at this and testing it out, it looks like your quotes in the regex are different from those in the csv.
" in the csv
"
” in the regex code.
”
To get the tweetid try this:
tweetid
B = FOREACH A GENERATE FLATTEN(REGEX_EXTRACT(line,'.*(,")',1)) AS (tweetid:long);