I'd render to MagixAVC with Mainconcept for a universally compatible file that's not too large to send. Give it a high enough maximum bitrate for scenes with detail.

I'd render to MagixAVC with Mainconcept for a universally compatible file that's not too large to send. Give it a high enough maximum bitrate for scenes with detail.

what presets is that?

I have been away from Vegas for a while but surprised so far some of the renders I have tried don't even play on my system which is part of why I made this post. for example the mp4 i just rendered wont open in qt player or Media Player. Clearly a deal breaker for anyone who would review the video...they would not wast the time.

I'd render to MagixAVC with Mainconcept for a universally compatible file ...

The recommendation was to use MAGIX AVC, but it looks like you've selected MAGIX HEVC which is why you're getting pop-up to buy the HEVC codec. AVC uses the years old H.264 compression standard whereas HEVC uses the more modern H.265 compression standard

Go to MAGIX AVC/AAC MP4 (the format just above HEVC) and select the template best matching your project (an '=' symbol should appear to the left of the best matching templates) but do not select any template with NEVC in the template name. The templates without NEVC use the Mainconcept AVC encode mode. To check this, click on Custom Template and look at the Encode Mode field.

CoPilot summarises the key differences between H.264 and H.265 as:

H.264 and H.265 are both video codecs, with H.265 offering better compression and quality at lower bitrates compared to H.264, making it ideal for high-resolution video streaming.

Overview of H.264 and H.265

H.264, also known as Advanced Video Coding (AVC), has been widely used since its introduction in 2003. It provides good compression efficiency and is compatible with a vast range of devices and platforms, making it suitable for various applications, including streaming, Blu-ray discs, and video conferencing.

H.265, or High Efficiency Video Coding (HEVC), is the successor to H.264, finalized in 2013. It improves upon H.264 by offering significantly better compression, allowing for the same video quality at about half the bitrate of H.264. This makes H.265 particularly advantageous for 4K and 8K video content. 

Key Differences

Compression Efficiency:

H.265 can compress video files by 25% to 50% more than H.264 while maintaining the same quality. This means that videos encoded with H.265 are generally smaller in size, which is crucial for streaming high-resolution content. 

Video Quality:

At the same bitrate, H.265 typically delivers sharper and more detailed images with fewer artifacts compared to H.264. This is due to H.265's ability to use larger coding tree units (CTUs) and more advanced encoding techniques. 

Compatibility:

H.264 has extensive support across a wide range of devices, including older hardware. In contrast, while support for H.265 is growing, some older devices may not support it natively. Most modern devices, however, are equipped to handle H.265. 

Use Cases:

H.264 is still widely used for online video streaming and is recommended for platforms like YouTube due to its compatibility and faster rendering times. H.265 is becoming the preferred choice for streaming services that offer 4K and higher resolutions, as it allows for better quality at lower bandwidths. 

Conclusion

Choosing between H.264 and H.265 depends on your specific needs. If you require compatibility with a wide range of devices and faster rendering, H.264 may be the better option. However, for high-resolution content where storage and bandwidth efficiency are critical, H.265 is the superior choice due to its advanced compression capabilities and improved video quality.