To create AI-generated videos for free, you can explore several user-friendly platforms:

Kapwing: This online editor has a basic AI generator that allows video creation with some limitations on file size and output. It's great for beginners who want to try out simple video editing and generation.
D-ID: Ideal for producing talking-head avatars, D-ID offers a good starting point for generating basic background videos using AI.
RunwayML: Although it primarily focuses on AI image editing, RunwayML also provides limited features for creating abstract video clips.

To maximize these free options, keep your videos short, ideally between 15-30 seconds. Plan your script in advance to make the most of any free trials.

For crafting effective prompts, focus on clarity and precision. Clearly define the elements you wish to incorporate in the video to guide the AI effectively.

Additionally, if you're exploring non-AI methods, consider using Pexels or Pixabay for stock footage combined with templates from online tools.

Remember that while these tools are helpful, developing a knack for editing will enhance your final output significantly.

Creating AI-generated videos can be a blast, and diving into platforms like Kapwing, D-ID, or RunwayML for free options is a great start. Kapwing's basic AI generator is perfect if you're just beginning, allowing you to experiment with short clips up to 30 seconds. D-ID excels at producing talking-head videos, which is fantastic for educational content or presentations. Meanwhile, RunwayML lets you play with abstract video creation, which could be an artistic outlet or the start of a creative project.

When crafting your prompts, aim for clarity and precision. For example, you could say, "Create a short video of a futuristic city at sunset, with flying cars and neon lights," to guide the AI effectively. If you're looking for inspiration or to learn from others, consider joining community projects on Kaggle or GitHub. You might even contribute to an AI film festival - how fun would that be?

As for remixing videos, platforms like Glitch offer tools for AI-driven mashups. Imagine DJing with visuals - it's a unique way to explore your creativity!

Regarding ChatGPT's Sora, it's a newer model focused on text-to-video generation. You might try prompts like, "Show a serene morning in a mountain village, with villagers starting their day," to see what it can produce. Keep experimenting, and remember, every little project you do adds up to bigger skills!