count and group_concat
WITH RECURSIVE cte1 AS (
SELECT videoid, 
       SUBSTRING_INDEX(ips, ',', 1) ip, 
       SUBSTRING(ips FROM 1 + LOCATE(',', ips) FOR 255) slack
FROM test
UNION ALL
SELECT videoid, 
       SUBSTRING_INDEX(slack, ',', 1) ip, 
       SUBSTRING(slack FROM 1 + LOCATE(',', slack) FOR 255) slack
FROM cte1
WHERE LOCATE(',', slack)
),
cte2 AS (
SELECT videoid, 
       ip 
FROM cte1
UNION
SELECT videoid, 
       slack 
FROM cte1 
WHERE !LOCATE(',', slack)
)
SELECT videoid, COUNT(ip) cnt
FROM cte2
GROUP BY videoid