I lost my old phone at a concert and got a new one but when I backed everything from the old phone to the new one it didn’t show in my new one if I get icloud will I get those videos back? Or how can I track my phone ?

It will only transfer those items that are in the backup or those in the cloud.

As for the lost phone, follow these steps: https://support.apple.com/en-us/HT201472

If the items were not restored from your backup, or if you did not use iCloud to sync devices, those items have been lost. You can check at iCloud.com to see if your data is there. If it is, enable iCloud sync for those services on your device (Settings > Apple ID > iCloud).

I can not find things from my old phone contacts pics etc.......please help