Advice needed for Ai tools

In my opinion, the most effective approach is to break down the script into smaller segments using AI tools to create short clips, then manually combine them with voiceovers using free editing software.

If this was possible that there is any free Ai tool is available to generate such a long videos then who waste their money on paid tools lol. There is no free tool which can generate such long videos about half an hour for free. Every Ai tool provides some free credits when you login just for try. One more thing that I don't think there is any tool available which can generate about 20 to 30 minute in one long prompt because Ai makes mistakes. So you have break your video script into scenes and then have to write a prompt of every scene to Ai then Ai generates the scenes step by step. Once you done then you have to edit them in video editor. In your case paid tools are the last option for you free tool can't help you in this regard.

Try Pictury's free plan - it caps videos at ten minutes so you'll have to split a 20-30 minute script into two or three parts, but the export quality is decent.

The maximum you can find is trial period for some video ai editor