Is the 'i' in 'videt' long or short?

The i in videt is short. The length of a vowel in classical Latin pronunciation is defined by its duration—its "quantity"—as opposed to its "quality", i.e. the nature of the sound: its waveform or timbre.

1. Is i a long or short vowel?
2. Is the i in ink long or short?
3. How do i know if it is short of i or long I?
4. What is the description of the i :/ sound?

Is i a long or short vowel?

SHORT VOWEL SOUND /i/

Is the i in ink long or short?

Yes, for my money the "i" in "ink" and "ring" is pronounced long e. Like in "creak" and "leak." I don't get the short i pronunciation with these words.

How do i know if it is short of i or long I?

The short i makes the vowel sound most commonly associated with the letter as seen in bit, clip, hid, and tip. The long i sound makes the sound of the name of the letter in question as seen in bite, hide, sight, and might.

What is the description of the i :/ sound?

The /ɪ/ sound is a Vowel sound and it's technical name is the 'Near-Close Near-Front Unrounded Vowel'. Remember that the key to pronunciation s physical and the name tells us about how the sound is made physically.