Video.js can't take video in mp4 - vue.js

Question

I want to take a video in mp4. But with this.player.recordedData, I'm taking only mkv format and I can't change it. So I was trying to use something like:
console.log(this.player.record().video);
But it's giving the error:
[Vue warn]: Error in render: "TypeError: Cannot read property 'name' of undefined",
TypeError: Cannot read property 'name' of undefined.
Here are the options:
player: '',
options: {
controls: true,
autoplay: false,
fluid: false,
loop: false,
width: 320,
height: 240,
bigPlayButton: false,
controlBar: {
volumePanel: false
},
plugins: {
record: {
audio: true,
video: true,
debug: true,
videoMimeType: 'video/webm;codecs=H264'
},
},
},
mounted() {
/* eslint-disable no-console */
this.player = videojs('#myVideo', this.options, () => {
// print version information at startup
var msg = 'Using video.js ' + videojs.VERSION +
' with videojs-record ' + videojs.getPluginVersion('record') +
' and recordrtc ' + RecordRTC.version;
videojs.log(msg);
});
// device is ready
this.player.on('deviceReady', () => {
console.log('device is ready!');
});
// user clicked the record button and started recording
this.player.on('startRecord', () => {
console.log('started recording!');
});
// user completed recording and stream is available
this.player.on('finishRecord', () => {
console.log(this.player);
var myfile = this.player.recordedData;
const chunks = [];
chunks.push(myfile);
this.attachments.push({
file: this.player.recordedData,
uploaded: 0
});
});
// error handling
this.player.on('error', (element, error) => {
console.warn(error);
});
this.player.on('deviceError', () => {
console.error('device error:', this.player.deviceErrorCode);
});
}