If your DMI and MA accouts are linked and you redeem in MA it will auto redeem the points to your DMI. You will get DMI points for purchases from linked providers from this list: https://moviesanywhere.com/collection/disney-movie-insiders
You can verify movies that were released 2019 and earlier, but you need to have already redeemed 5 codes that day. There is a limit of 5 codes every 24 hours. So if you try to redeem more than that you will get one of two errors. It will either say "limit reached" which means the points are good or it will say "Already redeemed" which means the points have been used.
For newer movies after 2019, you can redeem more than 5 per day so this doesn't work to verify points.