Using ‘will’ in japanese

I fell so idiotic asking this...
I have mastered how to use past tense in Japanese, however future tense always gives me a problem. How do I use will as an "I will", I would like to know how it works.

I have a video to make, everytime in the video I say "mirai" meaning future in place of "I will".

"I will make a video tonight/tommorow."

How do I say that in japanese and could you please explain to me how?

For the sentence you want to use, you just use the dictionary or masu form of the verb, which is tsukuru or tsukurimasu for make. When the verbs relate to future actions, there is no distinction between I will or going to.

If you want to convey a sense of certainty, you could add zettai ni, kitto or other similar words infront of the verb or object. For example, "zettai ni gemu wo tsukuru". Would best be translated as "I absolutely will make a game". These do have very strong meanings though, so in most cases you won't want to use them for general everday activities.

When communicating in Japanese, thinking of how a sentence would sound if it was literally translated to or from English will just cause you problems. They are not related languages, and both have their own nuances that don't always have equivalents. If you want to learn even the basics properly, it is better to understand the meaning (with English explanations if necessary), but begin to think using the logic and structure of the Japanse language.

To emphasize: there is no future tense in Japanese, the dictionary form serves as both present and future tense (for that reason it is sometimes called the "nonpast" tense).

Tomorrow I will go shopping.
明日、買い物に行きます。

In the most cases you can ignore "will" while the sentence in correct.

"I will make a video tonight/tommorow."
→ (Watashiwa) video wo konya/ashita tsukuri masu.
→ (Watashiwa) video wo konya/ashita tsukuru tsumiri desu.
They both sound almost similar while the sentence is correct in terms of common sense.

"will" can be referred as "tsumori".

As everyone has said, there is no "future" tense in Japanese verbs.

If you want to say "I will make a video tomorrow" in the sense of "I will definitely..." "I am determined to..." then adding "zettai ni" or "kitto ("definitely") would add that emphasis.

But if you are talking simple future, you can simply say
- Ashita bideo wo tsukurimasu. or
- Ashita bideo wo tsukuru.
...using the "-(r)u" or "-masu" form.

There is another way to say "I intend to..." which would be:
- Ashita bideo wo tsukuru tsumori desu.