Sample code does not work.

[GitHub King]

https://ffmpeg.xabe.net/tutorial.html

private static async Task RunConversion(Queue filesToConvert)
{
    while(filesToConvert.TryDequeue(out FileInfo fileToConvert))
    {
        //Save file to the same location with changed extension
        string outputFileName = Path.ChangeExtension(fileToConvert.FullName, ".mp4");
        await Conversion.ToMp4(fileToConvert.FullName, outputFileName).Start();
        await Console.Out.WriteLineAsync($"Finished converion file [{fileToConvert.Name}]");
    }
}

https://ffmpeg.xabe.net/docs.html

string output = Path.Combine(Path.GetTempPath(), Guid.NewGuid() + ".mp4");
var snippet = FFmpeg.Conversions.FromSnippet.Convert(Resources.MkvWithAudio, output);
IConversionResult result = await snippet.Start();

[GitHub King]

The first one seems to have been already reported by another user months ago.

The second one could be fixed with an "await".

var snippet = await FFmpeg.Conversions.FromSnippet.Convert....

[Mashnunul Huq]

Okay I might have solution to your problem. Mine is used for converting video into images. The documentation is for dotnet5. so in dotnet6 use conversions method instead of conversion method.
//Turn Video into images Func<string, string> outputFileNameBuilder = (number) => { return convertedVideoDir + "\\fileNameNo" + number + ".png"; };
IMediaInfo info = await FFmpeg.GetMediaInfo(testFilePath).ConfigureAwait(false);
IVideoStream videoStream = info.VideoStreams.First()?.SetCodec(VideoCodec.png);
IConversionResult conversionResult = await FFmpeg.Conversions.New().AddStream(videoStream).ExtractEveryNthFrame(2, outputFileNameBuilder).SetOutput(convertedVideoDir).Start();

[Tomasz Żmuda]

@HubKing
I've updated both examples in the documentation. If you see more issues feel free to tell me