Is it possible to move the videos from the SD card straight to iCloud?
No, it is not possible.
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1.
Try to free up iPad device storage see this Apple articles below:
If you need more space for an update on your iPhone, iPad, or iPod touch
If you need more space for an update on your iPhone, iPad, or iPod touch - Apple Support
How to check the storage on your iPhone, iPad and iPod touch
How to check the storage on your iPhone, iPad and iPod touch – Apple Support (UK)
Clear Other storage on your iPhone or iPad
Clear Other storage on your iPhone or iPad - Apple Support
2.
If you wish, you can upgrade the 5 GB free iCloud.
See -> What's the difference between device storage and iCloud storage?
What's the difference between device storage and iCloud storage? - Apple Support
See also the following Apple articles:
Upgrade to iCloud+ -> Upgrade to iCloud+ - Apple Support
iCloud+ plans and pricing -> iCloud+ plans and pricing - Apple Support
How to use iCloud on iPhone -> How to use iCloud on iPhone – Apple Support (UK)
Manage your iCloud storage -> Manage your iCloud storage - Apple Support